  United States Court of Appeals
      for the Federal Circuit
              __________________________

                     SOLVAY S.A.,
                   Plaintiff-Appellant,
                            v.
       HONEYWELL INTERNATIONAL, INC.,
              Defendant-Appellee.
              __________________________

                      2009-1161
              __________________________

    Appeals from the United States District Court for the
District of Delaware in case no. 06-CV-557, Judge Sue L.
Robinson.
                _________________________

               Decided: October 13, 2010
               _________________________

    ARTHUR I. NEUSTADT, Oblon, Spivak, McClelland,
Maier & Neustadt, P.C., of Alexandria, Virginia, argued
for plaintiff-appellant. With him on the brief were JEAN-
PAUL LAVALLEYE, BARRY J. HERMAN and JEFFREY B.
MCINTYRE. Of counsel was MICHAEL E. MCCABE, JR.

    ROBERT G. KRUPKA, Kirkland & Ellis LLP, of Los An-
geles, California, argued for defendant-cross appellant.
With him on the brief were LAURA M. BURSON, GUY
RUTTENBERG; and GREGORY F. CORBETT, of Washington,
DC. Of counsel were SEAN M. MCELDOWNEY, of Washing-
SOLVAY   v. HONEYWELL                                      2


ton, DC; and SHANI A. MOORE WEATHERBY, of Los Ange-
les, California.
                 __________________________

    Before DYK, MAYER, and SCHALL, Circuit Judges.
SCHALL, Circuit Judge.
    This is a patent case. It arises out of a suit by Solvay
S.A. (“Solvay”) against Honeywell Specialty Materials
LLC and Honeywell International, Inc. (collectively,
“Honeywell”) in the United States District Court for the
District of Delaware for infringement of U.S. Patent No.
6,730,817 (“the '817 patent”) owned by Solvay. Solvay
now appeals the final judgment of the district court in
favor of Honeywell dismissing Solvay’s suit. The court’s
judgment in favor of Honeywell was based on two rulings
on summary judgment. First, the court held that al-
though asserted claims 1, 5, 7, 10, and 11 of the '817
patent were infringed, they are invalid under 35 U.S.C.
§ 102(g)(2) because Honeywell was a prior inventor of the
subject matter of the claims who had not abandoned,
suppressed, or concealed its invention. 1 Solvay, S.A. v.
Honeywell Specialty Materials LLC, 591 F. Supp. 2d 729
(D. Del. 2008) (“Invalidity Ruling”). Second, the court
held that asserted claims 12-18, 21, and 22 of the '817
patent were not infringed by Honeywell. Solvay, S.A. v.
Honeywell Specialty Materials LLC, 591 F. Supp. 2d 724
(D. Del. 2008) (“Non-infringement Ruling”).
     For the reasons set forth below, we hold that the dis-
trict court erred in ruling claims 1, 5, 7, 10, and 11 of the

    1   Section 102(g)(2) states that “[a] person shall be
entitled to a patent unless . . . before such person’s inven-
tion thereof, the invention was made in this country by
another inventor who had not abandoned, suppressed, or
concealed it.”
3                                      SOLVAY   v. HONEYWELL


'817 patent invalid. We do so because we conclude that
Honeywell was not a prior inventor for purposes of
§ 102(g)(2). We also hold, however, that the district court
did not err in its rulings that claims 1, 5, 7, 10, and 11 of
the '817 patent were infringed and that claims 12-18, 21,
and 22 were not infringed. The judgment of the district
court is therefore affirmed-in-part and reversed-in-part.
The case is remanded to the district court for further
proceedings consistent with this opinion.
                       BACKGROUND
                             I.
    Solvay’s '817 patent has a priority date of October 23,
1995. The '817 patent is directed to methods for making
1,1,1,3,3-pentafluoropropane (“HFC-245fa”). HFC-245fa
has been found to be advantageous as a blowing and
insulation agent in the preparation of expanded polymeric
materials, of the type commonly used in refrigeration and
heat storage systems. See '817 patent, col.1 ll.12-14.
HFC-245fa is one of a group of non-ozone-depleting hydro-
fluorocarbons that were legislatively mandated to replace
ozone-depleting chlorofluorocarbons and hydrochloro-
fluorocarbons. The '817 patent discloses methods for
making            HFC-245fa            by          reacting
1,1,1,3,3-pentachloropropane (“HCC-240fa”) with hydro-
gen fluoride (“HF”) in the presence of a hydrofluorination
catalyst. Specifically, the patent claims processes for
making HFC-245fa that include continuously drawing off
gaseous HFC-245fa and hydrogen chloride (“HCl”) from
the reaction mixture.
    Claims 1 and 12 are the patent’s two independent
claims. Claim 1 reads as follows:
    In a process for the preparation of [HFC-245fa]
    comprising reaction of [HCC-240fa] with [HF] in
SOLVAY   v. HONEYWELL                                    4


    the presence of a hydrofluorination catalyst, the
    improvement which comprises carrying out the
    reaction at a temperature and under a pressure at
    which [HFC-245fa] is gaseous and isolating and
    [sic] [HFC-245fa] from the reaction mixture by
    drawing off [HFC-245fa] and [HCl] in a gaseous
    phase as each of said [HFC-245fa] and [HCl] is be-
    ing formed.
'817 patent, col.5 ll.36-46.
    Claim 12 reads as follows:
    In a process for the preparation of [HFC-245fa]
    comprising reaction of [HCC-240fa] with [HF] in
    the presence of a hydrofluorination catalyst, the
    improvement which comprises carrying out the
    reaction in a reactor equipped with a device for
    drawing off a gas stream at a temperature and
    under a pressure at which [HFC-245fa] is gaseous
    and wherein said device is controlled (a) to draw
    off a gas stream comprising [HFC-245fa] and
    [HCl] as each of said [HFC-245fa] and [HCl] is be-
    ing formed thereby isolating said [HFC-245fa]
    from the reaction mixture (b) to keep in the reac-
    tor in the liquid state the unconverted [HCC-
    240fa], most of the [HF] and most of the products
    of partial fluorination of [HCC-240fa].
Id. at col.6 ll.15-30.
                               II.
    Honeywell produces HFC-245fa in its plant located in
Geismar, Louisiana, by reacting HCC-240fa and HF in
the presence of a hydrofluorination catalyst (“the Geismar
process”). The Geismar process is a continuous process,
where HFC-245fa, HCl, unreacted HF, and other by-
products are drawn off from the reactor in gaseous form.
5                                      SOLVAY   v. HONEYWELL


Except for the catalyst that escapes from the reactor and
that is returned to the reactor by the reflux in the catalyst
stripper, the other components of the process exit the
reactor as a gas stream for further processing. Notably,
most of the HF (approximately 70%) that enters the
reactor subsequently leaves the reactor as part of the gas
stream. The gas stream then enters downstream equip-
ment, including an HF recovery unit which recovers
unreacted HF. The unreacted HF is later recycled and re-
fed, as a gas, to the reactor.
                            III.
     Solvay brought suit against Honeywell in the District
of Delaware, alleging that the Geismar process infringed
claims 1, 5, 7, 10-18, 21, and 22 of the '817 patent. In due
course, Honeywell moved for summary judgment of inva-
lidity of claims 1, 5, 7, 10, and 11 of the '817 patent.
Honeywell moved on the ground that, under 35 U.S.C.
§ 102(g)(2), it was a prior inventor of the claimed inven-
tion. For its part, Solvay cross-moved for summary
judgment of no invalidity on the ground that Honeywell
was not a prior inventor and that, even if it was, Honey-
well had abandoned, suppressed, or concealed its inven-
tion. For purposes of summary judgment on the validity
issue, the parties stipulated to the following facts:
    In early 1994, Honeywell (then AlliedSignal, Inc.) en-
tered into a research contract with the Russian Scientific
Center for Applied Chemistry (“RSCAC”). Pursuant to
the contract, RSCAC engineers performed process devel-
opment studies for the commercial production of HFC-
245fa. See Invalidity Ruling, 591 F. Supp. 2d at 732. In
July 1994, RSCAC sent a report to Honeywell in the
United States documenting that it had carried out the
liquid phase synthesis of HFC-245fa from HCC-240fa
using a continuous process. Id. The report documented
SOLVAY   v. HONEYWELL                                     6


that RSCAC had carried out a reaction of HCC-240fa and
HF in the presence of an antimony pentacholoride cata-
lyst using temperatures between 80-130 degrees Celsius
and pressures between 2-40 bar. Id. The report also
documented the resulting product yield, and it contained
a diagram of the equipment that RSCAC had used to
carry out the process. Id. It is undisputed that the proc-
ess the RSCAC engineers performed and reported to
Honeywell in July 1994 corresponds to the invention
claimed in Solvay’s '817 patent, and that RSCAC engi-
neers both conceived the invention and reduced it to
practice in Russia.
    In early 1995, Honeywell used the information that
RSCAC had provided to duplicate RSCAC’s experiments,
with similar conditions and equipment. Id. at 736 (noting
that Honeywell does not dispute that it replicated or
reproduced the work of the RSCAC engineers, such that
Honeywell “derived” the invention from RSCAC). It is
undisputed that Honeywell performed this work in the
United States prior to Solvay’s priority date of October 23,
1995.
    Throughout the summer of 1995, Honeywell contin-
ued working to develop and perfect its process for the
preparation of HFC-245fa. Id. at 733. The work included
finding optimum operating conditions for the process, as
well as designing and enabling downstream purification
of the HFC-245fa product. Id. Development of a pilot
plant to test a commercially viable manufacturing process
for HFC-245fa was begun by Honeywell, and the plant
was in successful operation by February 1996. In March
1996, Honeywell began drafting a patent application on
an improvement process for making HFC-245fa. The
application was filed on July 3, 1996, and eventually
issued as U.S. Patent No. 5,763,706 (“the '706 patent”).
The '706 patent discloses a process for the continuous
7                                       SOLVAY   v. HONEYWELL


preparation of HFC-245fa, using optimal conditions for
downstream purification, so that the HFC-245fa recov-
ered by distillation has a high purity (at least about
99.5%). See '706 patent, col.1 l.60-col.2 l.25; col.4 ll.40-42.
    On December 9, 2008, the district court granted Hon-
eywell’s motion for summary judgment of invalidity of
claims 1, 5, 7, 10, and 11 of the '817 patent and denied
Solvay’s motion for summary judgment of no invalidity.
See Invalidity Ruling, 591 F. Supp. 2d at 743. The court
ruled that Honeywell had previously made the invention
of the '817 patent in the United States in August 1995,
prior to the '817 patent’s priority date, and that the
asserted claims thus were invalid based on Honeywell
being a prior inventor under 35 U.S.C. § 102(g)(2). Id. at
739, 743.
    In arriving at its ruling, the court rejected Solvay’s
contention that Honeywell was not an “inventor” under
§ 102(g)(2). Solvay had urged that the invention at issue
was “conceived” abroad by RSCAC’s engineers and that
Honeywell’s “mere reproduction” of a foreign invention in
the United States did not make Honeywell an inventor
because an inventor must be involved in the conception of
the invention. The district court agreed that Honeywell
had to “demonstrate that it ‘conceived’ the invention at
issue,” to qualify as an inventor under § 102(g)(2), so that
“only ordinary skill in the art would be necessary [there-
after] to reduce the invention to practice.” Id. at 738. The
court did not agree, however, that reproduction of an
invention cannot satisfy § 102(g), or that, under
§ 102(g)(2), conception must first occur in the United
States. The court found “no authority” that barred Hon-
eywell from being an “inventor” for purposes of § 102(g)(2)
merely because it derived the invention from RSCAC as
“the original inventor.” In that regard, the court declined
“to read the ‘originality’ requirement of § 102(f) into
SOLVAY   v. HONEYWELL                                      8


§ 102(g),” 2 reasoning that “[s]ection 102(g) . . . contem-
plates multiple conceptions, as long as each inventor
‘appreciates’ his invention.” Id. at 739.
     The district court concluded that “Honeywell con-
ceived the invention at issue in the United States upon
receipt of RSCAC’s instructions, because it was at this
point that Honeywell possessed a definite and permanent
idea of the complete and operative invention, such that it
appreciated the fact of its invention.” Id. at 738. The
court also concluded that “Honeywell has demonstrated
conception by clear and convincing evidence as it is un-
disputed that its receipt of RSCAC’s instructions facili-
tated Honeywell's actual reduction to practice of the
invention.” Id. The court determined, therefore, that
Honeywell was the first inventor of the subject matter
claimed in the ′817 patent, unless it abandoned, sup-
pressed or concealed its invention. Id. at 739, citing 35
U.S.C. § 102(g)(2). The court reasoned that, in that
regard, the relevant inquiry concerned intentional sup-
pression, based on the period of delay between when
Honeywell received RSCAC’s instructions and when it
filed its own application that issued as the ′706 patent.
Id. The court found that “Honeywell was moving towards
public disclosure,” that Solvay had failed to show that
“Honeywell withheld its invention from the public ‘de-
signedly,’” and that, consequently, Honeywell had not
intentionally abandoned, suppressed, or concealed the
invention described in the ′706 patent. Id. at 742-43.
     The parties also cross-moved for summary judgment
on the issue of infringement of the '817 patent. Solvay
filed a motion for summary judgment of infringement of

    2   Section 102(f) states that “[a] person shall be enti-
tled to a patent unless . . . he did not himself invent the
subject matter sought to be patented . . . .”
9                                      SOLVAY   v. HONEYWELL


claims 1, 5, 7, 10, and 11. Honeywell, in turn, moved for
summary judgment of non-infringement of those claims
and also for summary judgment of non-infringement of
claims 12-18, 21, and 22. On December 9, 2008, the
district court ruled on the infringement issue. First, as an
alternative to its ruling that claims 1, 5, 7, 10, and 11
were invalid, the court granted Solvay’s motion for sum-
mary judgment of infringement of those claims and de-
nied Honeywell’s cross-motion for summary judgment of
non-infringement. Second, the court granted Honeywell’s
motion for summary judgment of non-infringement of
claims 12-18, 21, and 22.
     Following its summary judgment decisions, the dis-
trict court entered judgment in favor of Honeywell and
against Solvay, thereby dismissing Solvay’s suit. This
appeal followed. We have jurisdiction pursuant to 28
U.S.C. § 1295(a)(1).
                        DISCUSSION
                             I.
    We review a district court’s grant of summary judg-
ment de novo. Revolution Eyewear, Inc. v. Aspex Eyewear,
Inc., 563 F.3d 1358, 1365 (Fed. Cir. 2009). Summary
judgment is appropriate where there is no genuine issue
of material fact and the moving party is entitled to judg-
ment as a matter of law. Fed. R. Civ. P. 56(c); AquaTex
Indus., Inc. v. Techniche Solutions, 419 F.3d 1374, 1379
(Fed. Cir. 2005). Thus, summary judgment may be
granted when no “reasonable jury could return a verdict
for the nonmoving party.” Anderson v. Liberty Lobby,
Inc., 477 U.S. 242, 248 (1986).
    On appeal, Solvay argues that the district court erred
in holding that claims 1, 5, 7, 10, and 11 of the '817 patent
are invalid under 35 US.C. § 102(g)(2) on the ground that
SOLVAY   v. HONEYWELL                                     10


Honeywell was a prior inventor of the claimed subject
matter who had not abandoned, suppressed, or concealed
its invention. Solvay also argues that the district court
erred in granting summary judgment of non-infringement
of claims 12-18, 21, and 22. Solvay contends that the
district court’s non-infringement ruling was based on
faulty claim construction. For its part, Honeywell urges
us to affirm the judgment of the district court in its favor.
It contends that the district court did not err in ruling
claims 1, 5, 7, 10, and 11 of the '817 patent invalid and
claims 12-18, 21, and 22 not infringed. With regard to
claims 1, 5, 7, 10, and 11, Honeywell argues, as an alter-
native basis for affirming the judgment, that we should
reverse the summary judgment of infringement because
the ruling was based either on an erroneous claim con-
struction or a misapplication of the correct claim con-
struction. We address these contentions in turn.
                             II.
                             A.
     Solvay challenges on two grounds the district court’s
ruling that claims 1, 5, 7, 10, and 11 of the '817 patent are
invalid due to prior inventorship. First, Solvay argues
that Honeywell could not be “another inventor” under 35
U.S.C. § 102(g)(2) because it is undisputed that it did not
invent the claimed process for preparing HFC-245fa but,
rather, derived it from RSCAC, whose engineers invented
it in Russia. Solvay maintains that the court’s conclusion
that Honeywell was an inventor of the Russian invention
is contrary to 35 U.S.C. § 102(f), which provides that a
person shall be entitled to a patent unless “he did not
himself invent the subject matter sought to be patented.”
Honeywell could not be an “inventor” of the Russian
invention, Solvay reasons, because it did not itself invent
the subject matter of the invention. See Appellant’s Br. at
11                                     SOLVAY   v. HONEYWELL


17. According to Solvay, the district court erred when it
“decline[d] to read the ‘originality’ requirement of § 102(f)
into § 102(g).” See Invalidity Ruling, 591 F. Supp. 2d at
739. Solvay thus urges us to reject the district court’s
determination that “Honeywell . . . demonstrated concep-
tion by clear and convincing evidence as it is undisputed
that its receipt of RSCAC’s instructions facilitated Hon-
eywell’s actual reduction to practice of the invention.” Id.
at 738.
    Second, Solvay argues that, even if Honeywell does
qualify as “another inventor” under § 102(g)(2), the stat-
ute does not operate to render claims 1, 5, 7, 10, and 11
invalid because Honeywell suppressed and concealed both
the Russian invention and the invention claimed in its
own '706 patent. See Appellant’s Br. at 18. In short,
Solvay contends that Honeywell failed to carry its burden
of establishing by clear and convincing evidence that
claims 1, 5, 7, 10, and 11 are invalid. Young v. Lumenis,
Inc., 492 F.3d 1336, 1345 (Fed. Cir. 2007); Apotex USA,
Inc. v. Merck & Co., 254 F.3d 1031, 1037 (Fed. Cir. 2001)
(a party asserting invalidity under § 102(g)(2) must prove
facts by clear and convincing evidence establishing a prior
invention that was not abandoned, suppressed, or con-
cealed).
    Honeywell responds that we should affirm the judg-
ment of invalidity of claims 1, 5, 7, 10, and 11. First,
Honeywell argues that it is “another inventor” under 35
U.S.C § 102(g)(2) because it reduced the claimed inven-
tion to practice in the United States before the October
1995 priority date of Solvay’s '817 patent. See Appellee’s
Br. at 22. Honeywell bases this argument on the follow-
ing undisputed facts: (1) RSCAC performed in Russia a
process that corresponds to the invention of claims 1, 5, 7,
10, and 11 of the '817 patent; (2) in 1994, RSCAC trans-
mitted to Honeywell in the United States complete in-
SOLVAY   v. HONEYWELL                                     12


structions for the process; and (3) in early 1995, Honey-
well replicated the Russian process by following the
information provided by RSCAC, thereby practicing the
invention in the United States before the '817 patent’s
priority date. Id. at 23. Honeywell maintains that, under
these uncontested facts, it qualifies as “another inventor”
under § 102(g)(2), and that it is clear that Solvay was not
the first to make in the United States the subject matter
of claims 1, 5, 7, 10, and 11. Id. at 24. Citing Mycogen
Plant Sci., Inc. v. Monsanto Co., 243 F.3d 1316, 1332 (Fed.
Cir. 2001), and Henkel Corp. v. Procter & Gamble Co., 560
F.3d 1286, 1289 (Fed. Cir. 2009), Honeywell urges that a
showing that the claimed invention was previously re-
duced to practice in the United States by someone other
than the patentee is sufficient to establish a prior inven-
tion defense under § 102(g)(2). See Appellee’s Br. at 25-
26.
    Honeywell argues that we should reject Solvay’s con-
tention that Honeywell is precluded by § 102(f) from
obtaining a patent on the work performed by RSCAC and
that therefore it cannot be “another inventor” under
§ 102(g)(2). Id. at 26. According to Honeywell, § 102(f) is
not relevant to this case because there is no Honeywell
patent at issue here. Again citing Mycogen, Honeywell
states that the district court properly concluded that the
question of whether Honeywell itself is entitled to a
patent is not at issue in the case. Id. at 27. Relying on
Rexam Indus. Corp. v. Eastman Kodak Co., 182 F.3d
1366, 1370-71 (Fed. Cir. 1999), Honeywell urges that, in
order for § 102(g)(2) to apply, all that is required is that,
in the words of the statute, the “invention was made in
this country” before the '817 patent’s priority date. See
Appellee’s Br. at 28.
    In addition, in Dow Chemical Co. v. Astro-Valcour,
Inc., 267 F.3d 1334 (Fed. Cir. 2001), Honeywell argues, we
13                                    SOLVAY   v. HONEYWELL


rejected the contention that “another inventor” under
§ 102(g)(2) can only be the first original inventor. In
Honeywell’s view, Dow Chemical stands for the proposi-
tion that “someone qualifies as a prior inventor under
§ 102(g)(2) if the person made the invention in the United
States and ‘appreciated the fact of what he made.’” See
Appellee’s Br. at 28-29, citing 267 F.3d at 1341. Finally,
citing Checkpoint Sys., Inc. v. ITC, 54 F.3d 756, 761 (Fed.
Cir. 1995), Honeywell states that “[i]t would contradict
the purpose of § 102(g) to grant Solvay a patent covering
subject matter that Solvay was, as a matter of law, not
the first to invent.” See Appellee’s Br. at 31.
    Honeywell further argues that, once it established
that the claimed invention was made in the United States
by “another inventor” before the '817 patent’s priority
date, Solvay bore the burden of producing “evidence
sufficient to create a genuine issue of material fact as to
whether the prior inventor abandoned, suppressed, or
concealed the invention.” Id. at 31, citing Dow Chemical,
267 F.3d at 1339. According to Honeywell, Solvay failed
to carry that burden.
                            B.
    A person is not entitled to a patent if “before the ap-
plicant’s invention thereof the invention was made in this
country by another inventor who had not abandoned,
suppressed or concealed it.”       35 U.S.C. § 102(g)(2). 3

     3  Before enactment of the American Inventors Pro-
tection Act of 1999, Pub. L. No. 106-113, 113 Stat. 1501A-
552, on November 29, 1999, § 102(g)(2) prohibited an
applicant from receiving a patent if, prior to the appli-
cant’s invention, “the invention was made in this country
by another . . . .” 35 U.S.C. § 102(g)(2) (1994) (emphasis
added). In Dow Chemical, we held that, under both the
pre-1999 version of § 102(g)(2) and the current version of
the statute, which reads “the invention was made in this
SOLVAY   v. HONEYWELL                                    14


Section 102(g)(2) “relates to prior inventorship by another
in this country” and “retains the rules governing the
determination of priority of invention.” Kimberly-Clark
Corp. v. Johnson & Johnson, 745 F.2d 1437, 1444 (Fed.
Cir. 1984), quoting P.J. Federico, Commentary on the New
Patent Act, 35 USCA page 1, at 19 (1954). In other words,
when the statute uses the words “the invention was made
in this country,” it is referring to the act of inventing in
the United States. See Mycogen, 243 F.3d at 1331 (“[a]t
trial, Monsanto presented evidence that Monsanto scien-
tists Drs. Fischoff and Perlak were prior inventors, i.e.,
that they invented the subject matter of the '600 and '862
patents before Mycogen.”); Apotex, 254 F.3d at 1036
(“[t]he plain language of § 102(g) clearly requires that the
prior invention be made ‘in this country.’”). Therefore, the
issue we must decide is whether, under the facts of this
case, Honeywell “invented” in the United States the
process claimed in the '817 patent, as required by
§ 102(g)(2). For the following reasons, we hold that it did
not.
    As just seen, in Kimberly-Clark, we stated that
§ 102(g)(2) “relates to prior inventorship by another in
this country” and “retains the rules governing the deter-
mination of priority of invention.” 745 F.2d at 1444.
Those rules are well known. Section 102(g) states that, in
determining priority of invention, “there shall be consid-
ered not only the respective dates of conception and
reduction to practice of the invention, but also the reason-
able diligence of one who was first to conceive and last to
reduce to practice, from a time prior to conception by the

country by another inventor . . .” (emphasis added), it
must be shown that an “inventor” made the claimed
invention in order to establish a first-inventor defense.
267 F.3d at 1340. In this opinion, we refer to the current
version of § 102(g)(2).
15                                       SOLVAY   v. HONEYWELL


other.” 35 U.S.C. § 102(g)(2). Conception is the “forma-
tion, in the mind of the inventor, of a definite and perma-
nent idea of a complete and operative invention, as it is
hereafter to be applied in practice.” Hybritech, Inc. v.
Monoclonal Antibodies, Inc., 802 F.2d 1367, 1376 (Fed.
Cir. 1986), quoting 1 Robinson on Patents 532 (1890);
Coleman v. Dines, 754 F.2d 353, 359 (Fed. Cir. 1985); see
also Burroughs Wellcome Co. v. Barr Labs., Inc., 40 F.3d
1223, 1228 (Fed. Cir. 1994) (“Conception is complete only
when the idea is so clearly defined in the inventor’s mind
that only ordinary skill would be necessary to reduce the
invention to practice, without extensive research or
experimentation.”). Actual reduction to practice requires
that the claimed invention work for its intended purpose,
Hybritech, 802 F.2d at 1376, while constructive reduction
to practice occurs when a patent application on the
claimed invention is filed. Id.; Frazer v. Schlegel, 498
F.3d 1283, 1288 (Fed. Cir. 2007); Hyatt v. Boone, 146 F.3d
1348, 1352 (Fed. Cir. 1998).
     We have regularly applied “the rules governing the
determination of priority of invention” in cases involving
the question of prior inventorship under § 102(g)(2). See,
e.g., Mycogen, 243 F.3d at 1332 (“Monsanto has two ways
to prove that it was the prior inventor: (1) it reduced its
invention first . . ., or (2) it was the first party to conceive
of the invention and then exercised reasonable diligence
in reducing that invention to practice.”); Dow Chemical,
267 F.3d at 1339-41 (considering conception and reduction
to practice in a § 102(g)(2) case). The question thus
becomes whether Honeywell conceived of the invention at
issue and reduced it to practice in the United States, such
that Honeywell is “another inventor” of the process
claimed in the '817 patent under § 102(g)(2).
   Honeywell is not “another inventor” under § 102(g)(2).
That is clear from the facts set forth above, which are
SOLVAY   v. HONEYWELL                                      16


undisputed. As noted, working pursuant to RSCAC’s
research contract with Honeywell, Russian engineers
conceived of the process for making HFC-245fa in Russia.
Thereafter, in July 1994, RSCAC sent a report to Honey-
well in the United States relating to the developmental
work the RSCAC engineers had performed. In the report,
RSCAC described the liquid phase synthesis of HFC-
245fa from HCC-240fa and the resulting product yield.
The report also contained a diagram of the equipment
that RSCAC had used to carry out the process. Finally, in
the report, RSCAC stated that it had carried out a reac-
tion of HCC-240fa and HF in the presence of an antimony
pentachloride catalyst using temperatures between 80-
130 degrees Celsius and pressures between 2-40 bar. In
the words of the district court, “it is uncontested that the
Russian engineers, working under contract with Honey-
well manufactured HFC-245fa from HCC-240fa using a
continuous process in May 1994 and disclosed that work
to Honeywell in a July 1994 report sent to the United
States.” See Invalidity Ruling, 591 F. Supp. 2d at 736.
    The district court concluded, however, that Honeywell
conceived the invention because, “upon receipt of
RSCAC’s instructions . . . Honeywell possessed a definite
and permanent idea of the complete and operative inven-
tion, such that it appreciated the fact of its invention.” Id.
at 738. The district court further concluded that Honey-
well had “demonstrated conception by clear and convinc-
ing evidence” and “that its receipt of RSCAC’s
instructions facilitated Honeywell’s actual reduction to
practice of the invention.” Id. The court stated that
§ 102(g) exists to determine which of several conceptions
occurred first and thus contemplates multiple conceptions
so long as each inventor “appreciates” his invention. Id.
at 739.
17                                     SOLVAY   v. HONEYWELL


     Conception is “the formation in the mind of the inven-
tor, of a definite and permanent idea of the complete and
operative invention, as it is hereafter to be applied in
practice.” Burroughs Wellcome Co. v. Barr Labs., Inc., 40
F.3d at 1228 (quoting Hybritech Inc. v. Monoclonal Anti-
bodies, Inc., 802 F.2d at 1376. The test for conception is
whether the inventor had an idea that was definite and
permanent enough that one skilled in the art could un-
derstand the invention. Burroughs Wellcome, 40 F.3d at
1228. In this case, Honeywell did not have, or formulate,
a definite and permanent “idea” of its own capable of
being reduced to practice. Rather, it reproduced the
invention previously conceived and reduced to practice by
RSCAC in Russia. Such reproduction cannot be concep-
tion because, if it were, the result would be that one who
simply followed another inventor’s instructions to repro-
duce that person’s prior conceived invention would, by so
doing, also become an “inventor.” Although the district
court declined to read the “originality” requirement of 35
U.S.C. § 102(f) into § 102(g), originality is, nevertheless,
inherent to the notion of conception. 4 The definition and
test of conception employed in Burroughs Wellcome, which
speaks to the formation of an idea in the mind of the
inventor, necessitates that the conception of an invention
be an original idea of the inventor. 5 Since it is undisputed


     4  Webster’s Third New International Dictionary de-
fines “conception,” relevantly, as “the originating of some-
thing (as an idea or plan) in the mind. syn see IDEA.”
(emphasis added). WEBSTER’S THIRD NEW INTERNATIONAL
DICTIONARY 469-470 (3d ed. 1986).
    5   This does not negate the district court’s observa-
tion that § 102(g) is directed to the determination of
which invention was first conceived. Inventors, acting
independently of each other, can conceive the same inven-
tion, and § 102(g) guides the resolution of who receives
priority.
SOLVAY   v. HONEYWELL                                    18


that Honeywell did not originate the invention, but repro-
duced it in the United States by following RSCAC’s in-
structions, Honeywell cannot be said to have conceived of
the invention and cannot, consequently, be an inventor for
purposes of § 102(g)(2). The district court erred by not
applying the requirement that Honeywell be an original
inventor of the process disclosed in claims 1, 5, 7, 10, and
11 of the '817 patent.
     Honeywell relies on Mycogen Plant Sci., Corp. v. Mon-
santo Co. and Henkel Corp v. Procter & Gamble Co. for
the proposition that prior inventorship under § 102(g)(2)
may be established by showing that the claimed invention
was previously reduced to practice in the United States by
someone other than the patentee. In Mycogen, the issue
was whether prior inventorship under § 102(g)(2) was
established based on showing an earlier conception and
later reduction to practice coupled with reasonable dili-
gence during the “critical period,” i.e., the time between
the patentee’s later conception date but earlier reduction
to practice date. 261 F.3d 1361-62. We held that sub-
stantial evidence supported patent invalidity under
§ 102(g)(2), based on “prior inventors” having been dili-
gent during the required time period up to the patentee’s
reduction to practice date. Id. at 1370. There was no
contention that the “prior inventors” had not independ-
ently, on their own, conceived the invention in the United
States. Honeywell, of course, did not independently, on
its own, conceive of the invention at issue in this case in
the United States. Rather, RSCAC’s engineers first
conceived the invention in Russia.
    Honeywell’s reliance on Henkel also is misplaced.
Henkel involved an appeal from a patent interference
decision awarding priority of invention to the party that
demonstrated an earlier actual reduction to practice
based on “an appreciation” that the invention at issue
19                                    SOLVAY   v. HONEYWELL


worked for its intended purpose. 560 F.3d at 1289.
Henkel did not involve the situation presented here: an
accused infringer claiming to be “another inventor” under
§ 102(g)(2) when it did not conceive the invention at issue.
     Similarly unhelpful to Honeywell is its reliance on
Dow Chemical Co. v. Astro-Valcour, Inc. for the proposi-
tion that “someone qualifies as a prior inventor under
§ 102(g)(2) if the person made the invention in the United
States and ‘appreciated the fact of what he made.’” See
Appellee’s Br. at 29. In Dow Chemical, Astro-Valcour,
Inc. reduced to practice a process for producing plastic
foam in the United States by following, and then improv-
ing upon, the teachings of a U.S. patent. 267 F.3d at 1341
n.5. This court held that Astro-Valcour, Inc. “recognized
and appreciated” its new process such that it qualified as
a “prior inventor” under § 102(g)(2) even if it was unaware
that it had created a legally patentable invention, and
was not the first inventor to appreciate the patentability
of the invention. 267 F.3d at 1341. Unlike the party
seeking the benefit of § 102(g)(2) in Dow Chemical, who
actually conceived the pertinent invention, Honeywell did
not conceive the invention at issue in this case. Dow
Chemical simply held that, outside the priority context,
an individual can have conceived the invention, and be an
inventor, even though he did not appreciate what he had
invented. The fact that Honeywell later improved upon
RSCAC’s instructions to create a new process of making
HFC-245fa and claimed that process in its '706 patent is
immaterial for the purposes of assessing Honeywell’s
prior invention defense under § 102(g)(2). The invention
at issue is the invention claimed in Solvay’s '817 patent,
not the one claimed in Honeywell’s '706 patent. The
critical point is that Honeywell did not conceive the
invention of the '817 patent, but derived it from others.
SOLVAY   v. HONEYWELL                                     20


    Finally, Honeywell argues that, as a matter of policy,
it would contradict the purpose of § 102(g)(2) to allow
Solvay to have a patent covering subject matter that
Solvay was not the first to invent. The problem with this
argument is that it misstates the issue before us. The
issue before us is not whether Solvay was the first to
invent the subject matter of the '817 patent. Rather, the
issue is whether Honeywell established its defense that
the invention claimed in the '817 patent was conceived
and reduced to practice by it, as “another inventor” in the
United States, before Solvay. The uncontested facts make
it clear that Honeywell did not establish its § 102(g)(2)
defense.
    Whether this holding ignores the realities of global-
ization and outsourcing by modern-day research compa-
nies, as Honeywell contended at oral argument, is not the
question before us. The question before us is whether,
under the undisputed facts, Honeywell qualifies as “an-
other inventor” under 35 U.S.C. § 102(g)(2). Because
Honeywell did not itself conceive the RSCAC process of
making HFC-245fa, under 35 U.S.C. § 102(g)(2), as this
court has construed the statute, it is not “another inven-
tor” of the subject matter claimed in the '817 patent.
    In sum, because Honeywell does not qualify as “an-
other inventor” under 35 U.S.C. § 102(g)(2), we hold that
the district court erred in ruling claims 1, 5, 7, 10, and 11
of Solvay’s '817 patent invalid by reason of prior inventor-
ship. 6 We turn now to Honeywell’s argument that the
district court erred in its ruling that Honeywell infringed
claims 1, 5, 7, 10, and 11 and to Solvay’s challenge to the

    6   Because Honeywell does not qualify as “another
inventor” under § 102(g)(2), it is not necessary for us to
reach the question of whether Honeywell abandoned,
suppressed, or concealed the invention claimed in the '817
patent.
21                                     SOLVAY   v. HONEYWELL


court’s ruling that Honeywell did not infringe claims 12-
18, 21, and 22.
                            III.
    “An infringement analysis entails two steps. The first
step is determining the meaning and scope of the patent
claims asserted to be infringed. The second step is com-
paring the properly construed claims to the device ac-
cused of infringing.” Markman v. Westview Instruments,
Inc., 52 F.3d 967, 976 (Fed. Cir. 1995) (en banc) (citations
omitted), aff’d, 517 U.S. 370 (1996). Claim construction is
a question of law, which we review de novo. Cybor Corp.
v. FAS Techs., Inc., 138 F.3d 1448, 1456 (Fed. Cir. 1998)
(en banc).
                             A.
Honeywell contends the district court erred in its alterna-
tive ruling granting summary judgment of infringement
of claims 1, 5, 7, 10, and 11 of the '817 patent. Honeywell
states that “[e]ither the court misapplied its construction
of the ‘isolating’ limitation [of independent claim 1], or it
misconstrued the ‘isolating’ limitation . . . by not limiting
the gas stream containing the ‘isolat[ed] [HFC-]245fa to
only residual amounts of reaction mixture components.”
Appellee’s Br. at 21. Honeywell argues that, applying the
correct claim construction, it is entitled to a judgment of
non-infringement of independent claim 1 and dependent
claims 5, 7, 10, and 11. Honeywell’s argument involves
the construction of both claims 1 and 12 of the patent, for
Honeywell asserts that “[h]ad the district court properly
applied the construction it gave to ‘isolating . . . [HFC-
245fa] from the reaction mixture’ for claim 12, it could
only have concluded, as a matter of law, that the accused
Honeywell process does not infringe claim 1 or its depend-
ent claims.” Id. at 57.
SOLVAY   v. HONEYWELL                                    22


     The district court construed the limitation “isolat-
ing . . . [HFC-245fa] from the reaction mixture by drawing
off [HFC-245fa] and [HCI] in a gaseous phase as each of
said [HFC-245fa] and [HC1] is being formed” in inde-
pendent claim 1 as follows:
   The process for making HFC-245fa includes a re-
   action at a temperature and under a pressure
   whereby HFC-245fa and HCI are produced in
   gaseous form and separated from the reaction mix-
   ture in a gas stream that can include other com-
   pounds, such as unconverted reactants and
   chlorofluoropropanes possibly formed by incom-
   plete fluorination of HCC-240fa.
Solvay, S.A. v. Honeywell Specialty Materials LLC, No.
06-557, 2008 WL 5155629, at *2 (D. Del. Dec. 9, 2008)
(“Claim Construction Ruling”) (emphasis added).
    The corresponding limitation in independent claim 12
of the '817 patent reads “isolating said [HFC-245fa] from
the reaction mixture . . . to keep in the reactor in the
liquid state the unconverted [HCC-240fa], most of the
[HF] and most of the products of partial fluorination of
[HFC-245fa].” In construing this limitation, the district
court stated:
   I conclude that the “isolating” limitation found in
   claims 1 and 12 should be construed consistently.
   The fact that claim 12 discloses a device to accom-
   plish the process, while claim 1 only describes the
   process, does not convince me that the patentee
   meant to use the same word (“isolate”) to describe
   different processes.
Claim Construction Ruling, 2008 WL 5155629, at *3. The
court construed the “isolating” limitation of claim 12 as
follows: “As the HFC-245fa and HCI are produced in
23                                    SOLVAY   v. HONEYWELL


gaseous form, they are separated from the reaction mix-
ture in a gas stream by the device.” Id. at *4. Thus, the
court construed “isolating” in independent claims 1 and
12 as meaning “separating.”
    In arriving at its construction of claim 1, the district
court considered whether the term “isolating,” as used in
the claim, means that “only” HFC-245fa and HCI are
drawn off from the reaction mixture in a gas stream as
they are being formed, or whether the gas stream can
include other components. The court reasoned that the
patent specification uses “isolate,” “separate,” and “to
draw off” interchangeably, as did the inventors during
prosecution, and that “isolate” thus should not be con-
strued to mean only HFC-245fa and HCI, even if the
dictionary definition of “isolate” suggests separation of a
“pure chemical substance.” Id. at *3. The court also
reasoned that because claim 12’s use of “isolate” clearly
allows for “residual amounts” of products other than HFC-
245fa and HCI to be in the gas stream, the isolating
limitation of claim 1 “should be construed consistently.” 7
    In its infringement ruling, the district court held that
the Geismar process infringed claim 1 because it draws off
a gas stream from the reaction mixture and thereby
isolates, or separates, HFC-245fa from the mixture. See
Non-infringement Ruling, 591 F. Supp. 2d at 727. The
court noted that “although the gas stream in the Geismar
process includes many compounds other than HFC-245fa
and HCl,” the process still infringed because “claim 1 has
been construed very broadly . . . .” Id. at 727-28.



     7  As seen, claim 12 recites that “most of the [HF]
and most of the products of partial fluorination of [HFC-
245fa]” are kept in the reactor in the liquid state (empha-
ses added). '817 patent, col.6 ll.28-30.
SOLVAY   v. HONEYWELL                                   24


     Honeywell urges that the district court failed to ap-
preciate that claim 1 requires that the gaseous product
leaving the reactor include only “residual amounts of
other non-reacting compounds,” along with HFC-245fa
and HCI. According to Honeywell, that is also what claim
12 requires. In support of its argument, Honeywell points
to the expert testimony of Michael Doherty interpreting
“isolating” as “purifying” HFC-245fa from all other reac-
tion mixture components so that there are only residual,
i.e., not measurable, amounts of other compounds in the
gas stream. See Appellee’s Br. at 59-60. Honeywell also
points to dictionary definitions of “isolation” as “separa-
tion of a pure chemical substance from a compound or
mixture,” contending “isolating” thus means completely
separating HFC-245fa from all other reaction mixture
components, including HF. Id. at 60-61. Finally, Honey-
well asserts that, during prosecution, the inventors lim-
ited the “isolating” step to being one that separates
HFC-245fa and HCl from all reaction mixture components
the first (and only) time they leave the reactor in a gas
stream. Id. at 62. 8 Honeywell concludes that the district
court’s error—either in claim construction or claim con-
struction application—resulted in an incorrect finding of
infringement with respect to Honeywell’s Geismar process
because, in that process, more than “residual amounts” of
other compounds leave the reactor. Honeywell contends
that the Geismar process does not isolate from the reac-
tion mixture the HFC-245fa and HCl as they are being

   8    Honeywell points to an amendment made during
prosecution, in which the inventors added the “isolating”
language in claim 1 and overcame prior art by describing
their process as isolating HFC-245fa and HCl by drawing
off each from the reaction mixture as they are being
formed. Honeywell notes that the inventors said nothing
about also drawing off reaction mixture components, such
as HF. Id.
25                                     SOLVAY   v. HONEYWELL


formed, but, rather, draws off a gas stream which is
mostly HF and which also contains partially fluorinated
compounds. Id. at 58.
    Solvay responds that the district court erred in nei-
ther its claim construction nor its application of that
claim construction. Solvay argues that the district court
correctly construed claim 1 when it concluded that “isolat-
ing” does not mandate that HFC-245fa and HCl are the
only materials in the gas stream that are drawn off, or
isolated, from the reaction mixture. See Non-infringement
Ruling, 591 F. Supp. 2d at 727-28. Solvay asserts that
the district court correctly understood that the '817 patent
teaches a process that separates gaseous HFC-245fa from
the reaction mixture in the reactor by continuously draw-
ing off a gaseous stream that includes HFC-245fa and
HCl, as well as other components. See Appellant’s Reply
Br. at 29-30. Solvay contends that the district court
properly construed the “isolating” limitation to include
this teaching. See Non-infringement Ruling, 591 F. Supp.
2d at 728 (noting that the broad construction of claim 1
“reflect[s] the claim language and the intrinsic evidence”).
See Appellant’s Reply Br. at 30-31. Solvay also contends
the district court properly applied the construction of the
“isolating” limitation to find infringement, based on
Honeywell’s acknowledgement that its Geismar process
includes many compounds other than HFC-245fa and HCl
in the gas stream that are drawn off from the reaction
mixture (e.g., HF and other partially fluorinated com-
pounds). See id. at 31; Non-infringement Ruling at 727-
28.
    We see no error    in the district court’s infringement
ruling. In our view,   claim 1 is not limited to “isolating”
only HFC-245fa and     HCl and residual amounts of other
compounds.     The     claim does not recite isolating
HFC-245fa from all     other components involved in the
SOLVAY   v. HONEYWELL                                   26


process, and it does not recite isolating HFC-245fa from
everything beyond residual amounts of reaction mixture
components in the gas stream. Neither does the specifica-
tion require that the gaseous stream separated from the
reaction mixture contain only HFC-245fa and HCl. The
patent specification uses the terms “isolating,” “separat-
ing,” and “drawing off” interchangeably, as the district
court noted. At the same time, we do not think any of the
statements made during prosecution call for a construc-
tion of claim 1 that requires only “residual amounts” of
other components in the gas stream. In the prosecution
amendment to which Honeywell points, see footnote 8
above, the inventors simply described their process as
isolating HFC-245fa and HCl by drawing off each from
the reaction mixture as they are being formed. Such a
description does not constitute a statement that the
invention of the '817 patent involves a process in which
only certain reactants (and no others) can be isolated from
reaction mixture components or, in other words, one in
which only residual amounts of other compounds are
contained in the gas stream.
    Honeywell’s reliance on the testimony of Michael Do-
herty interpreting “isolating” as “purifying” HFC-245fa
from all other reaction mixture components is misplaced.
The term “purifying” is not used in the patent and is not
to be considered synonymous with “isolation” based on
extrinsic expert testimony alone. See Phillips v. AWH
Corp., 415 F.3d 1303, 1317 (Fed. Cir. 2005) (en banc)
(extrinsic evidence such as expert testimony is “less
significant than the intrinsic record in determining the
legally operative meaning of claim language”) (internal
citations omitted); Kara Tech. Inc. v. Stamps.com Inc.,
582 F.3d 1341, 1348 (Fed. Cir. 2009) (“extrinsic sources
like expert testimony cannot overcome more persuasive
intrinsic evidence.”); Ultimax Cement Mfg. Corp. v. CTS
27                                    SOLVAY   v. HONEYWELL


Cement Mfg. Corp., 587 F.3d 1339, 1347 (Fed. Cir. 2009)
(district court erroneously relied on expert testimony and
a dictionary definition to the exclusion of the intrinsic
evidence of the specification language).
    Finally, we do not view the district court’s construc-
tion and application of claim 1 as inconsistent with its
construction of claim 12. As noted, in construing claim
12’s “isolating” limitation, the court stated that “[a]s the
HFC-245fa and HCl are produced in gaseous form, they
are separated from the reaction mixture in a gas stream
by the device.” Claim Construction Ruling, 2008 WL
5155629, at *4. The court’s construction of claim 1, in
which “isolating” does not mean that the gas stream
contains no more than residual amounts of components
other than HFC-245fa and HF, is not at odds with its
construction of claim 12’s isolating limitation, in which
“HFC-245fa and HCl are . . . separated from the reaction
mixture in a gas stream . . . .”
    The district court construed a different claim 12 limi-
tation, “to keep in the reactor in the liquid state the
unconverted [HCC-240fa], most of the HF and most of the
products of partial fluorination of [HCC-240fa],” as fol-
lows:
     The gas stream can include residual amounts of
     other compounds, such as unconverted reactants
     and chlorofluoropropanes possibly formed by in-
     complete fluorination of HCC-240fa. However, the
     unconverted HCC-240fa, more than 50% of the
     HF, and more than 50% of the partially fluori-
     nated intermediates must remain in the reactor
     vessel in the liquid state.
Claim Construction Ruling, 2008 WL 5155629, at *4
(emphasis added). In urging an inconsistency between
the court’s construction of the “isolating” limitations in
SOLVAY   v. HONEYWELL                                      28


claims 1 and 12, Honeywell points to this claim construc-
tion language. It apparently contends that this construc-
tion of claim 12’s “to keep in the reactor in the liquid
state” limitation, combined with the court’s statement
that claims 1 and 12 are to be construed “consistently,”
means that “isolating” in claim 1 means that only “resid-
ual” amounts of compounds other than HFC-245fa and
HCl may be in the gas stream. This language, however,
does not relate to the “isolating” limitation of claim 12.
Rather, it relates to the “keep in the reactor in the liquid
state” limitation of the claim. As the discussion in section
B below makes clear, this is a fundamentally different
limitation from the “isolating” limitation.
    We therefore reject Honeywell’s argument with re-
spect to claim 1, whether viewed as asserting an incorrect
claim construction or the erroneous application of a
correct claim construction. Because Honeywell does not
dispute that its accused Geismar process has a gas stream
with more than residual amounts of reaction mixture
components, the district court did not err in ruling that
claims 1, 5, 7, 10, and 11 of the '817 patent were in-
fringed.
                             B.
    Solvay argues that the district court erred in granting
summary judgment of non-infringement of claims 12-18,
21, and 22 of the '817 patent, see Non-infringement Rul-
ing, 591 F. Supp. 2d at 728. Specifically, Solvay contends
the district court erred in its construction of the limitation
“to keep in the reactor in the liquid state the unconverted
[HCC-240fa], most of the [HF] and most of the products of
partial fluorination of [HCC-240fa]” in independent claim
12. Solvay urges that, under the correct construction of
the limitation, there is no dispute that the Geismar
process infringes claims 12-18, 21, and 22. According to
29                                      SOLVAY   v. HONEYWELL


Solvay, all other limitations of claim 12 and dependent
claims 13-18, 21, and 22 are met in the Geismar process.
    As noted, the district court construed this limitation
as follows:
     The gas stream can include residual amounts of
     other compounds, such as unconverted reactants
     and chlorofluoropropanes possibly formed by in-
     complete fluorination of HCC-240fa. However, the
     unconverted HCC-240fa, more than 50% of the
     HF, and more than 50% of the partially fluori-
     nated intermediates must remain in the reactor
     vessel in the liquid state.
Claim Construction Ruling, 2008 WL 5155629, at *4. In
so ruling, the court looked to the prosecution history, in
which claim 12 was described by the inventors as being
“limited” to a process whereby the reaction is carried out
in a reactor “equipped with a device for drawing off a gas
stream which is controlled . . . to keep in the reactor in the
liquid state the unconverted HCC-240fa, most of the HF
and most of the products of partial fluorination of HCC-
240fa.” Id. The court concluded that, on this prosecution
record, “claim 12 is a more limited, narrow claim than
claim 1 and should be construed accordingly.” Id.
    Armed with its claim construction, the court ruled
that the Geismar process did not infringe claim 12, or
dependent claims 13-18, 21, and 22, because the Geismar
process does not keep more than 50% of the HF in the
reactor vessel in the liquid state, as required by the claim.
See Non-infringement Ruling, 591 F. Supp. 2d at 728.
The court cited the portion of the record referring to
Honeywell’s description of its Geismar process, which
Solvay did not dispute, characterizing the Geismar gas
stream as containing unreacted HF and partially fluori-
nated intermediates, along with other components. Id. at
SOLVAY   v. HONEYWELL                                    30


726. The record also reflects that the gas stream in the
Geismar process is fed, inter alia, into an HF recovery
unit to recover the unreacted HF, which is later re-fed to
the reactor as a gas, not a liquid.
    In arguing against the district court’s claim construc-
tion, Solvay breaks up the limitation into two parts; first
addressing the “to keep in the reactor” clause and then
addressing the “in the liquid state” clause. Solvay con-
tends that the “to keep in the reactor” clause should be
read to include unconverted and partially converted
reactants that are either “kept in” or “returned to” the
reactor for further use in the process, and that it was
error for the court to conclude that the reactants must
always remain in the reactor vessel. See Appellant’s Br.
at 29-30. Solvay points to language in the specification
which teaches that “it is advantageous to separate the
[HFC-245fa] and the [HCl] from the reaction mixture as
they are being formed and to keep in, or return to, the
reactor the unconverted reactants. . . .“ See '817 patent,
col.2 ll.64-67 (emphasis added); Appellant’s Br. at 28-29.
    As for the “in the liquid state” clause, Solvay argues
that a correct construction of the limitation overall should
include HF that leaves the reactor but then returns (in
any state, either liquid or gaseous) and thereby becomes
available to react in the liquid phase reaction to produce
HFC-245fa, as disclosed in the specification. See Appel-
lant’s Br. at 28-30. Solvay maintains that the district
court’s non-infringement ruling should be reversed,
because it is based upon an erroneous claim construction
and that the Geismar process infringes claim 12 under a
correct claim construction that permits reactants to
remain in the process by being returned to the reactor.
    For its part, Honeywell contends the district court
correctly construed the claim 12 limitation based on the
31                                     SOLVAY   v. HONEYWELL


plain language of the claim, the '817 patent specification
and the prosecution history. Honeywell contends that its
Geismar process does not infringe claim 12 of the '817
patent under that construction, because most of its HF
leaves the reactor, and re-enters the reactor as a gas, not
a liquid. See Appellee’s Br. at 15. Honeywell argues that
the district court properly relied on the plain language of
the claim to construe “keep in” to mean that most of the
HF must actually remain in (not leave from and return to)
the reactor. Id. at 44-45. Honeywell points to the sen-
tence in the '817 patent specification upon which Solvay
relies (“to keep in, or return to, the reactor the uncon-
verted reactants”) and contends that it discloses two
distinct actions—(1) “to keep in” and (2) “or return to”—
and that claim 12 covers the former alone. Honeywell
also argues that, during prosecution, the inventors limited
the claimed invention to keeping unconverted and par-
tially converted reactants in the reactor by distinguishing
the invention over prior art, U.S. Patent No. 5,574,192
(“the '192 patent”), which disclosed removing HF as a gas
from the reactor, condensing it, and then later recycling
(i.e., returning) it back to the reactor. Id. at 52-53. Hon-
eywell contends the district court properly recognized that
claim 12 is “a more limited, narrow claim than claim 1”
because it was described as making “even more apparent”
the advantage of the claimed invention over the '192
patent, by limiting the process of claim 12 to require a
device that is controlled “to keep in the reactor in the
liquid state . . . most of the [HF].” See Claim Construction
Ruling, 2008 WL 5155629, at *2, *4; Appellee’s Br. at 44-
45.
    Here, again, we agree with the district court’s claim
construction. In our view, the limitation “to keep in the
reactor in the liquid state” means that the reactants must
stay in the reactor in the liquid state until they leave as a
SOLVAY   v. HONEYWELL                                    32


gas and cannot return after being re-processed. It is true
that the disclosure in the specification is broad enough to
include unconverted and partially converted reactants
that return to the reactor for further use in the process,
because the “or” in the phrase “to keep in, or return to,
the reactor the unconverted reactants” suggests an alter-
native description of the process rather than either/or, in
the disjunctive sense. However, the prosecution history
should also be considered, and here we think the issue is
decided. See, e.g., Phillips, 415 F.3d at 1317 (“the prose-
cution history can often inform the meaning of the claim
language by demonstrating how the inventor understood
the invention and whether the inventor limited the inven-
tion in the course of prosecution, making the claim scope
narrower than it would otherwise be.”).
     During prosecution, the inventors distinguished the
prior art '192 patent from their invention on the ground
that, in their invention, the reactants are not recycled and
returned to the reactor, but rather have the advantage of
remaining in the reactor vessel in the liquid state. The
statements made during prosecution reflect a distinction
between, on the one hand, the claimed invention having
reactants remain in the reactor in liquid form and, on the
other hand, the prior art having unconverted and par-
tially converted reactants leave and then return to the
reactor for re-processing. The claim 12 limitation ex-
cludes the step of having reactants return to the reactor.
It is undisputed that, under this construction, the term
“keep in the reactor in the liquid state” is not met by the
Geismar process. See Non-infringement Ruling, 591 F.
Supp. 2d at 726 (“[t]he record also reflects that the gas
stream is fed, inter alia, into an HF recovery unit to
recover the unreacted HF, which is later re-fed, as a gas,
to the reactor”). Thus, we see no error in the district
33                                     SOLVAY   v. HONEYWELL


court’s ruling that the Geismar process does not infringe
claims 12-18, 21, and 22 of the '817 patent.
                        CONCLUSION
     We reverse the district court’s grant of summary
judgment that claims 1, 5, 7, 10, and 11 of the '817 patent
are invalid under 35 U.S.C. § 102(g)(2). However, we
affirm the ruling on summary judgment that Honeywell’s
Geismar process infringes claims 1, 5, 7, 10, and 11. We
also affirm the court’s ruling on summary judgment that
the Geismar process does not infringe claims 12-18, 21,
and 22 of the '817 patent. We remand the case to the
district court for further proceedings consistent with this
opinion.
                           COSTS
     Each party shall bear its own costs.

 AFFIRMED-IN-PART, REVERSED-IN-PART, and
               REMANDED.
