Georgia Kaolin Company (hereafter called appellant) is a New Jersey corporation engaged at its Dry Branch, Georgia plant in the processing of clay for use in the paper coating trade. It originally brought this suit on September 22, 1949 against Thiele Kaolin Company (hereafter called appellee), a Georgia corporation also competitively engaged in clay processing for the paper coating industry, charging infringement of its Maloney patent,1 from appellee's manufacture and sale of certain commercial grades of paper coating clay2 at its Sandersville, Georgia plant. The original complaint sought the usual injunctive relief and damages, and in its answer appellee interposed, inter alia, the usual, basic defenses of non-infringement and invalidity of the patent, both as failing to disclose patentable invention as a matter of law and as anticipated, in fact, by numerous other prior art patents and uses.3

At a pre-trial conference held on February 11, 1950, it was agreed between the parties that the issues thus raised were "properly referable" for trial before a Special Master, and the district court so ordered.4 The Master agreed upon, John Gilbert, Esquire, subsequently held two lengthy hearings beginning on September 11, 1950 and February 5, 1951, at which a voluminous amount of testimony was taken on both issues of validity and infringement. After preparing an initial report sustaining validity, but finding non-infringement, and considering extensive oral and written objections thereto filed by both parties, the Master filed a final report with the district court on September 29, 1952, substantially adhering to his previous view that the Maloney patent was valid, but had not been infringed.

The district court adopted the above stated conclusions of the Master on June 19, 1953, in an order from which an appeal was initially taken to this Court but subsequently dismissed because of doubt as to finality of the decision. On October 23, 1953, appellant filed a supplemental complaint charging further infringements by "different products (and) proccesses" made and employed by appellee "subsequent to the filing of the original complaint," and trial before the Master thereon, to which appellee filed an answer that its products and processes were then "identical in every material respect with the processes and products which the Master's Report found do not infringe the patent in suit." On that same date, the district court's prior order of June 19, 1953, purporting finally to adopt and confirm the Special Master's final report of September 29, 1952, was, by agreement of the parties, "vacated, pending final judgment in view of supplemental complaint," and appellee's aforementioned counterclaim was withdrawn.

The issues thus drawn by the supplemental complaint and answer were not again referred to the Master for trial, but a hearing thereon was held before the district court on November 30, 1953, at which time testimony was taken and the court informally restated its impression, announced at a former hearing held on August 5th, that its previous order confirming the Master's report was a "final judgment" and "res adjudicata" with respect to any allegations of the same or similar acts of infringement previously considered. However, in its formal opinion, thereafter filed on July 26, 1954, the court found "that defendant's processes and products charged as infringements are the same processes and same products complained of in the original complaint and do not infringe said patent," and concluded that neither grade Nos. 1 nor 1B of appellee's accused clay products infringed the Maloney patent. The court's final judgment simultaneously filed expressly confirmed the Master's report, held the Maloney patent valid but not infringed, and independently adjudicated dismissal of both the original and supplemental complaints, so that all issues before the court, as well as those previously considered by the Master and reviewed by it, were finally resolved. On August 9, 1954, appellant filed the main appeal from the findings of the Master and court below on non-infringement, and on August 20, 1954, appellee filed its cross-appeal attacking their conclusions as to validity.

Validity of the Maloney Patent.

The Maloney patent was originally filed on November 26, 1934, and issued May 16, 1939,5 to a corporate predecessor of appellant, as assignee of the inventor, William T. Maloney. To facilitate an intelligent understanding of the arguments pro and con validity, claims 5, 9 and 10 of the patent, here alleged to be infringed by appellee's grades No. 1 and 1B clays, are fully quoted in the margin.6

As its language reveals, claim 5 is a "process claim" which teaches a method for treating crude Georgia clay so as to produce "a finely divided material adapted for use in place of satin white in coating paper," whereas "product claims" 9 and 10 are essentially descriptive of the end product of the process disclosed in claim 5, also similarly described in terms of its function as "a finely divided material adapted for use in place of satin white in paper-coating compositions * * *." (Emphasis ours.) Claim 5 more particularly describes that "finely divided material" as a clay fraction "containing colloidal particles and non-colloidal smaller particles at least about 80% of which are of a size between 0.1 and 2 microns and adapted to impart * * * gloss and color when applied to paper." (Emphasis again ours.) Claim 9 speaks somewhat vaguely of precipitating the aqueous (water and clay) suspension under "controlled conditions", otherwise undefined, to recover a clay fraction also described as "consisting of colloidal and non-colloidal smaller particles of which at least about 80% are between 0.1 and 2 microns, inclusive, in size, and in such proportions (not definitely stated) as to impart * * * gloss and color, etc." (Emphasis also ours.) Finally, though it also contains the somewhat obscure "under controlled conditions" phrase, claim 10 alone uniquely requires "at least 90%" of the clay particles to be "of a size two microns and smaller and in such proportions (also not definitely stated) as to impart * * * gloss and color, etc." (Emphasis ours.)

Appellee contests the validity of the Maloney patent principally on four grounds: (1) Its alleged anticipation by, and failure to disclose patentable invention over, certain prior art patents and references not expressly considered by the Patent Office before issuance;7 (2) because of Maloney's alleged attempt to monopolize an unpatentable natural product and phenomena of nature;8 (3) alleged invalidity of the single "process claim", as well as of both "product claims" in issue, for describing Maloney's contribution, if any, purely in functional terms at the precise point of his asserted novelty;9 and (4) finally, because of alleged ambiguity and uncertainty in other italicized portions of the claims resulting from Maloney's failure to disclose any specific method of control and the precise proportions of the various size clay particles desired; and particularly in his failure, in each claim, to specify any commercially recognized method (such as Calbeck & Harner, Bouyoucas or Casagrande) for testing the stated percentages of clay particles within his supposedly "critical" 0.1-2 micron control range.10

With reference to appellee's first contention as to invalidity for anticipation and failure to disclose invention over the prior art, we think Maloney's teachings probably disclose a patentable contribution over the "finer (clay particle) the better theory" attributable to the prior art patentees, Stocker and Rafton, and also deserve independent recognition over the course, wire-mesh, screening processes of Edgar and Callighan. See footnote 7, supra.11

Though the contention has some force, we think appellee's second argument, that the claims are invalid as attempting to monopolize an unpatentable natural product and phenomena of nature, is also insufficient to justify invalidation of the patent, since it unfairly minimizes the novelty and utility of Maloney's process in materially improving the physical properties of the natural clay product for the paper coating industry, so as substantially to reduce the need for "satin white"; and in producing an improved clay fraction which imparted greater gloss and color than possible with theretofore known "H. T. clay", so as to render its use commercially more advantageous to the paper coating industry and justify its patentability. Cf. Vincent v. Suni-Citrus Products Co., 5 Cir., 215 F.2d 305; see Rumford Chemical Works v. New York Baking Powder Co., 2 Cir., 134 F. 385.

We likewise reject appellee's third insistence, supra, as to invalidity of the claims for their functional language, since this argument emphasizes the functional aspects of their disclosure (i. e., in terms of the result or product produced), without according sufficient weight to the overall process or treatment concept whereby Maloney was enabled to produce the improved clay product. See Minnesota Mining & Mfg. Co. v. International Plastic Corp., 7 Cir., 159 F.2d 554, 558; cf. Montgomery v. Marzall, 88 U.S.App.D.C. 281, 189 F.2d 640, 643.

Finally, though we regard this last issue as close and debatable, we are disposed to reject appellee's argument as to invalidity of the claims for alleged ambiguity in their disclosure. Cf. Fruit Treating Corp. v. Food Machinery Corp., 5 Cir., 112 F.2d 119, 121; Cold Metal Process Co. v. Republic Steel Corp., D.C., 123 F. Supp. 525. In so holding, we rely upon the fact that all three claims, though somewhat vague and uncertain in the particulars heretofore noted (see italicized portions of claims), nevertheless do otherwise speak in express language of a 0.1-2 micron control range and stated "percentages", which terms are sufficiently definite and precise to overcome the deficiencies urged and import patentability. In this connection, we note that the use of such similar, indefinite terms and phrases as "about", "sufficient * * * to enhance", slight excess, substantial space, etc., to permit a reasonable tolerance in commercial practice of inventions, has been held insufficient to invalidate claims for alleged ambiguity in their disclosure, so that we do not feel justified, upon this practically de novo judicial review on validity, in holding the claims invalid upon this ground.12 There are decisions recognizing that a patentee is not inexorably required, upon penalty of forfeiting his statutory monopoly, either precisely to describe, or fully appreciate, the nature of the changes wrought by his process which result in production of the product desired.13

Even though we confess some doubt as to the validity of the Maloney claims over this Court's recent decision in Vincent v. Suni-Citrus Products Co., supra, and its expressions in the Fruit Treating Corporation case, supra, we also feel a compelling reluctance to invalidate the Maloney patent upon this belated judicial review, and without benefit of any specific findings on validity below; especially since, in spite of the claim deficiencies now urged, his patent has through many intervening years since its issuance after prolonged consideration by the Patent Office apparently enjoyed an extensive commercial success, along with much trade recognition and competitor acceptance.14 Irrespective, however, of its utility and commercial success, we think that the Maloney patent, as disclosing a mere improvement process and product in a fairly well developed field, does not merit such pioneer recognition in the paper coating industry as would now justify any broad construction of his claims for infringement purposes and with the tolerance requested. We, therefore, conclude that the Maloney patent, if valid at all, is only so when confined within the limits of his claimed "2 micron control point" contribution; and that, when the claims are thus narrowly construed under the findings below, they were properly held not infringed by appellee's accused process and products by the Master and district court, as will hereinafter more fully appear. See Universal Oil Products Co. v. Globe Oil & Refining Co., 322 U.S. 471, 484, 64 S. Ct. 1110, 88 L. Ed. 1399; Phillips Petroleum Co. v. Shell Oil Co., 5 Cir., 166 F.2d 384; Aluminum Co. of America v. Thompson Products, 6 Cir., 122 F.2d 796; Price-Trawick, Inc., v. Gas Lift Corporation, 5 Cir., 101 F.2d 134; Cf. Southern States Equipment Corp. v. USCO Power Equipment Corp., 5 Cir., 209 F.2d 111; Stewart-Warner Corp. v. Lone Star Gas Co., 5 Cir., 195 F.2d 645.

The Infringement Issue.

Appellant here insists (1) that the district court erred in adopting the Special Master's conclusion, supposedly implicit in his findings, that infringement of the Maloney patent could be proved only by showing that appellee made use of the Calbeck & Harner measuring apparatus in its accused process and product; (2) that it further erred in rejecting proof of appellee's clay particle measurements, as evidenced by its published specifications and trade representations, which is allegedly conclusive on infringement; and (3) finally, that it particularly erred in failing to find infringement under the supplemental complaint via adoption of appellee's insistence that its previous order confirming the Master's report was "res adjudicata" on the infringement issue, even though that order was vacated and the proof under the supplemental complaint was allegedly different.

We agree, however, with appellee's insistence that the above arguments in large measure misconceive the true basis of the findings and judgment below, and are also insufficient to justify reversal upon the infringement issue.

With specific reference to the first proposition urged, and considering the report in its entirety, we view the pertinent findings of the Master15 as having only evidentiary significance along with other factual conclusions of non-infringement,16 and do not think they should be accorded any controlling weight as impliedly restricting and limiting the claims and proof of infringement, as alleged, to the use of the Calbeck and Harner measurement method alone. That the failure of the claims and proof to show any precise method of measurement was only one of the grounds upon which the Master predicated his ultimate conclusion of non-infringement is illustrated by such other findings as there is "no accurate and accepted means of determining the proportion of clay below 0.1 micron",17 appellee's accused process does not "effect a separation from the suspension of particles above a predetermined size range" (Finding No. 50, quoted in footnote 16, supra), and "there is no evidence * * * that any accused clay * * * is adapted on a commercial basis for use in place of satin white" (Finding No. 62, footnote 16, supra). The last quoted conclusion of the Master alone, from the proof adduced under the original complaint, might be sufficient to support his conclusion of non-infringement, since all three claims expressly require that infringing clay be "adapted for use in place of satin white", and there is testimony credited by the Master tending to reveal that the accused type clays were not actually adapted to replace this substance in the paper-coating trade.18 Moreover, even adopting appellant's insistence that any commercial method of testing for clay particle size should not be construed as a limitation upon Maloney's claims for infringement purposes, under the present record we still cannot say that infringement, as a matter of law, has been made out, or that the contrary findings of the Master and district court on this issue are so "clearly erroneous" as to require reversal.19 In a patent case where the controlling facts are without significant dispute, infringement may conceivably become a question of law for an appellate court, but where, as here, the testimony is in sharp conflict on material particulars, infringement must of necessity be viewed as a question of fact to be resolved by the fact finder on a credibility basis like any other factual issue. See Fritz W. Glitsch & Sons, Inc., v. Wyatt Metal & Boiler Works, 5 Cir., 224 F.2d 331. Though an occasional injustice may result, we think it by far the better practice in patent litigation, as elsewhere, for the essential facts to be resolved at the fact-finding level,20 than for appellate courts without clear warrant to usurp the fact-finding function.

Much of the above discussion is also referable to appellant's second contention as to the court's alleged error in rejecting proof of infringement by appellee's own particle size determinations by the Bouyoucas method, as well as by its published specifications and trade representations. In the latter connection, however, we think it should be noted that appellee's specification and trade circular has consistently throughout this litigation shown different grades of clay with differing particle sizes and prices, and even represents that "other grades can be made according to the customer's specifications", presumably by varying such production factors as concentration of suspension, dispersing agent, settling time, etc. Cf. Vincent v. Suni-Citrus Products Co., supra, 215 F.2d at page 314; see also Master's Finding No. 48, footnote 15, supra. Appellee has never disputed its practice of controlling clay particle sizes, but only insists that it does not control them within the fair intendment of the monopoly asserted under the Maloney claims, requiring "separation from the suspension of particles above a predetermined size range, etc." Under the facts found, which we cannot fairly reject as lacking in the required evidentiary support, we think appellee's representations in this regard may not reasonably be viewed as conclusive proof of infringement.

Finally, though we think that the district court, having vacated its previous order confirming the Master's report, might more appropriately have also referred the substantially similar issues posed by the supplemental complaint for trial before him, the determination to review only that portion of the proceeding was discretionary with the court, and we think no abuse of its discretion in this regard appears, or substantial prejudice to appellant resulting therefrom has been shown which would now justify re-opening this already prolonged litigation. Of course, the court's use of the phrase "res adjudicata" at the August 5th hearing now appears inappropriate, in view of its subsequent vacation of its confirmation order, but we think it clear from the colloquy between court and counsel at the hearing on the supplemental complaint and from its opinion and judgment heretofore partially quoted under the validity section, supra, that the court was not actually basing its decision against appellant on any principle of "res adjudicata", but upon an independent factual finding of non-infringement, even though it chose to attach a strong presumption to the Master's findings because it also found that appellee's then accused processes and products were not significantly different from those which the Master and court had previously considered under the original complaint.21 Under the present record, we think those conclusions of the court are not without evidentiary support, and that they furnish an adequate factual and legal basis for the judgment rendered, so that the judgment should be, and is hereby

Affirmed.