This patent infringement suit involves a chemical product used on citrus groves for the control of rust mites, greasy spot, mela-nose, and scab, called “Hexide” by plaintiff patent holder and “Super-Hex” and “Hexaphene-LV” by defendants. Plaintiff Nationwide Chemical Corporation (and two companies allied in interest with Nationwide) brought suit on a patent developed by defendant Wilburn T. Wright and assigned to Nationwide when Wright was its president. Now in business for himself, Wright contended in the district court that Nationwide’s patent is invalid, but, even if the patent is valid, that the amount of hexachlorophene his products use and the method of application are sufficiently different so as not to infringe. The district court held Nationwide’s patent valid, but not infringed, in extensive findings of fact and conclusions of law reported in
Nationwide Chemical Corp. v. Wright,
An extensive repetition of all the facts and law is unnecessary. We only focus here on the specific arguments brought to this Court on appeal, and only reflect on those facts needed to premise our decision. Defendants have not appealed the findings of patent validity and Nationwide’s entitlement to various foreign patent rights. Nationwide does not contend that it established the existence of a trade secret. The sole issue on appeal is whether defendants induced infringement of Nationwide’s United States Patent No. 3,420,936, specifically, Claims 1, 2, and 4 thereof. 1
*716 It should be noted that this case must be approached as a straight patent infringement suit. Because of the inequity in Wright’s having developed the patent, limited its claims, and then accomplished on his own the same purpose in a slightly different manner, we have carefully scrutinized this record for error. The result, however, must turn on whether or not defendants’ actions would infringe, had they been those of an unrelated third party. We do not have before us a breach of trust action or any other theory which would affect the outcome of the case, other than patent infringement.
In brief, Nationwide’s patent called for use of hexachlorophene “at an effective dosage of less than 4 ounces per acre,” applied to “both the upper and under surfaces of the foliage of the plants and to the soil adjacent thereto.” Defendants’ products called for use in amounts greater than 4 ounces per acre, only to the surface of citrus plants. This difference was found to be sufficient to prevent infringement.
Judge Krentzman gave three independent grounds for his finding of noninfringement.
First,
he found that Nationwide had “specifically and intentionally limited the claims to ‘less than four ounces per acre’ in the face of a long and continued rejection by the Examiner” of Nationwide’s application. Accordingly, he held that Nationwide was estopped by the doctrine of file wrapper estoppel from extending its coverage to dosages of hexachlorophene of greater than 4 ounces per acre.
Second, he concluded that “the amendment of the claims in [Nationwide’s] application to include the limitation to the treatment of specific pathogenic micro-organisms for specific plants constitutes an intentional limitation of the claims in order to avoid the prior art relied on by the Examiner and to secure allowance of the claims in question.” In addition, Nationwide had argued before the patent office that the application of hexachlorophene to different plants was unpredictable. This was confirmed by the trial testimony of various expert witnesses. For these reasons, the court held that the doctrine of file wrapper estoppel prevents Nationwide from claiming that its patent covers use on pathogenic micro-organisms attacking citrus, regardless of the dosage of hexachlorophene applied. Id. at 839 (Conclusions of Law E and F).
Third, Judge Krentzman ruled that infringement was not proved because there was no evidence that defendants had induced anyone to apply defendants’ products “both to the upper and under surfaces of the foliage of the plants and to the soil adjacent thereto,” as required in Nationwide’s patent claims. Id. at 840 (Conclusion of Law G).
We affirm on the basis of the first and third grounds above, that is, that file wrapper estoppel prevents plaintiffs from claiming coverage for dosages of hexachloro-phene greater than 4 ounces per acre, and that plaintiffs failed to prove that defendants instructed application of their products to the soil adjacent to the plants. We do not reach the question of whether file wrapper estoppel prevents plaintiffs from claiming coverage for use of hexachloro-phene on citrus. With this limitation, we adopt Judge Krentzman’s excellent opinion.
We think it might be useful, however, to supplement Judge Krentzman’s opinion with a comment or two of our own.
I. Application to the Surface of the Ground Adjacent to the Plant Has Not Been Proven
Nationwide’s patent claim clearly requires hexachlorophene to be applied “to the surfaces of said plant and to the surface of the ground adjacent thereto ” (emphasis added). The patent specifications show that application to the soil adjacent toi the *717 plants was an important step in Nationwide’s invention:
The purpose of this invention is to provide simultaneous control of both foliage diseases which attack the plant and also control of soil-borne diseases which attack the same plants.
An important object of this invention is to provide novel contact-type nonphyto-toxic compositions of matter for combating and controlling diseases or infections of growing plants by the application, of my novel compositions as a spray of dust, to the soil in which the plants are growing and to the plants themselves.
The importance of control of the harmful bacteria in the surface layer of soil not only immediately surrounding the growing plants but also in borders of fields surrounding the plants and along adjacent road sides and the like has been demonstrated by my investigations and experiments.
(Emphasis added). In addition, one of plaintiffs’ expert witnesses testified that if hexachlorophene were applied to the plant and also applied to the ground, there would be a “much better chance of controlling the disease” then if just one or the other method of application were used. He explained the reason for this to be that the diseases are caused by soil-borne micro-organisms, which spend part of their life cycle in the soil, so that treating the soil significantly reduces the number of disease carrying organisms.
A patent is not infringed where any of the steps which constitute the patented method or process is omitted.
See, e. g., Engelhard Industries, Inc. v. Research Instrumental Corp.,
We have reviewed the entire record, and find no evidence in the record that defendants’ products were ever applied directly to the soil adjacent to the plants. Indeed, the only evidence is to the contrary. Defendant Wright testified that Hexachlorophene-LV “is prepared solely for aerial application.” The labels and instruction data for both Hexachlorophene-LV and Super-Hex call for aerial spray application to the plants.
Nationwide, however, asks us to infer that “[sjuch aerial spray application inherently leads to treatment of the adjacent soil as well,” thus constituting indirect evidence that defendants’ products were applied to the soil. There is no evidence in the record to support any such assumption, nor is the conclusion so self-evident that we could take judicial notice of it. Indeed, as defendants counter, if the plants’ leaves are sufficiently thick, aerial application would not result in application of the product to the surface of the ground adjacent to the plant. In the absence of any evidence in the record to support the assumption urged on us by plaintiffs, we do not believe that aerial application leads to the application to the adjacent soil intended by Nationwide’s patent and necessary for it to be infringed.
We need also remember that the trial court’s finding of fact is protected by Rule 52(a), Fed.R.Civ.P., and cannot be overturned on appeal unless clearly erroneous.
See, e. g., Ziegler v. Phillips Petroleum Co.,
II. The Doctrine of File Wrapper Estop-pel Limits Nationwide’s Patent to Dosages of “Less Than Four Ounces Per Acre”
Nationwide argues that the “less than 4 ounces per acre” limitation was inserted into the amended claims only to point out the difference from the high dosage, 48 ounces per acre of the prior art (the Potato Journal article). Thus, Nationwide contends that its invention covers all “low dosages” of hexachlorophene, not just dosages of “less than 4 ounces per acre” as found by the district court. In support of its argument, Nationwide cites our cases which say that “an applicant should not be presumed to have made a disclaimer broader than necessary to yield to the actual challenge to his claim.”
Ziegler v. Phillips Petroleum Co.,
Nationwide concedes that it had to insert some dosage limitation in order for its patent claims to be accepted. This is especially obvious when it is realized that Nationwide withdrew the grandparent application and submitted the parent application with its “less than 4 ounces per acre” limitation immediately after a rejection by the Examiner in which he noted that
With regard to the proportions involved, it must be noted that applicant’s claims either fail to recite proportions or are drawn to proportions both lesser than and greater than that reported in the reference publication [the Potato Journal article], Obviously the proportions are not critical.
(Emphasis added). Thus, some dosage limitation was required “to yield to the actual challenge to [Nationwide’s] claim.”
If the Nationwide had amended its claim to say that it claimed the use of hexachloro-phene in “low dosages,” perhaps its claim would have been allowed by the Examiner; but by the same token, perhaps it would not have been allowed. If that was not allowed, perhaps the Examiner would have allowed a limit of less than 8 ounces per acre, or perhaps less than 5 ounces per acre. We do not know. That is the problem with Nationwide’s argument. It has a certain surface appeal, because of the large gap between the prior art reference of 48 ounces per acre and Nationwide’s limitation of 4 ounces per acre, and the closeness of Wright’s dosages to Nationwide’s. The difficulty, however, is that it would cause us to place ourselves in the Examiner’s place, and either guess what he would have allowed if faced with the question, or substitute our judgment for that of the Examiner, who is the expert in this field.
The simpler solution is to look at the question of whether the patentee had to insert a limitation in the broader sense. It is clear beyond dispute that Nationwide had to put some limit on its dosages of hexachlorophene. In that sense, its amendment was required by the Examiner’s rejection of Nationwide’s earlier claims based on the prior art. Since some dosage limitation was required, we do not ask if the specific 4-ounce limitation itself was required. For whatever reason, that is the embodiment of its claim which Nationwide chose. Having chosen that limitation, Nationwide is es-topped from asking the Court to give it a broader coverage than it chose for itself.
The case most nearly on point is not
Ziegler
or
Hunt, supra,
but
Ekco Products Co. v. Chicago Metallic Manufacturing Co.,
We agree with the Seventh Circuit. Since Nationwide was forced to introduce some dosage restriction, and chose the “less than 4 ounces per acre” restriction as the embodiment of its claim, we look no further, and hold Nationwide “strictly to the letter of the limited claims granted” to it. This case, as did Ekco, involves a situation where the purportedly infringing process employed a dosage that fell between the limitation in the patent in suit and the prior art. Rather than reexamine the application to decide what in that gap the Examiner might have allowed the patentee to claim, we strictly limit the patentee to what he claimed. The Hunt-Ziegler presumption, supra, that the patentee did not make a disclaimer “broader than necessary to yield to the actual challenge to his claim,” has no application in the present situation.
The
Hunt-Ziegler
presumption does apply in two different situations. In situations where the purported infringer falls on the other side of the patent in suit from the prior art, the patent in suit may be entitled to some slight range of equivalents. Thus, if Nationwide had limited its claim to a dosage of 2 to 4 ounces, and Wright had used 1 ounce, the
Hunt-Ziegler
presumption
might
apply and entitle Nationwide to a limited range of equivalents below 2 ounces.
Cf. Kolene Corp. v. Motor City Metal Treating, Inc.,
The second situation where the
Hunt-Ziegler
presumption may apply is that exemplified by
Ziegler
itself, that is, situations where the limitation in the claim was
not
inserted to overcome any prior art. Thus, in
Ziegler,
Ziegler amended its patent claim for a catalyst by adding the language, “essentially consisting of” two components. This amendment was inserted to overcome the Examiner’s objection that the original claim was too broad and did not disclose enough.
For the reasons discussed in the portions of the district court’s excellent opinion which we have adopted, as supplemented by the above comments, we hold that defendants have not induced the infringement of Nationwide’s patent.
AFFIRMED.
Notes
. Claims 1, 2 and 4 of Nationwide’s patent, entitled “Combating Bacterial and Fungal Plant Diseases with Hexachlorophene 2,2'-Methylene Bis-(3,4,6-Trichlorophenol),” are as follows:
1. The method for combating infections in plants growing in soil infested with pathogenic micro-organisms including bacterial spot (Xanthomonas vesicatoria) of peppers and tomatoes, angular leaf spot (Pseudomo-nas lachrymans) and downy mildew (Pero-nospora cubensis) of cucumbers, damping off (Rhizoctonia) of beans and cabbage, and damping off and sore shin (due to Rhizocto-nia) of cotton, which comprises applying to the surfaces of said plant and to the surface of the ground adjacent thereto a composition containing as an active ingredient 2,2'-methy-lene bis-(3,4,6-trichlorophenol), said active ingredient being applied at an effective dosage of less than 4 ounces per acre.
2. The method according to claim 1 in which the composition is applied as an aqueous spray containing the 2,¿’-methylene bis-(3,4,6-trichlorophenol) at a concentration within the range 100-1200 p.p.m.
******
4. The method of protecting a crop growing in soil infected with parasite micro-organisms including bacterial spot (Xanthomonas vesicatoria) of peppers and tomatoes, angular leaf spot (Pseudomonas lachrymans) and downy mildew (Peronospora cubensis) of cucumbers, damping off (Rhizoctonia) of beans and cabbage, and damping off and sore shin (due to Rhizoctonia) of cotton, which comprises applying to the upper and under surfaces of the foliage of said crop and to the surface of the soil immediately under and adjacent the plants of said crop, a bactericidal composition containing as a principal ac *716 tive ingredient, 2,2'-methylene-bis-(3,4,6-tri-chlorophenol) immediately after the primary bacterial infection period, said composition being applied at an effective rate of not more than four ounces per acre.
