Noranda Mines v. Minerals Separation Corp.

Noranda Mines v. Minerals Separation Corp.
Collection
Supreme Court Judgments
Date
1949-12-05
Report
[1950] SCR 36
Judges
Kerwin, Patrick; Rand, Ivan Cleveland; Kellock, Roy Lindsay; Estey, James Wilfred; Locke, Charles Holland
On appeal from
Canada
Subjects
Intellectual property
Decision Content
Supreme Court of Canada
Noranda Mines v. Minerals Separation Corp., [1950] S.C.R. 36
Date: 1949-12-05
Noranda Mines Limited (Defendant) Appellant;
and
Minerals Separation North American Corporation (Plaintiff) Respondent.
1949: March 30, 31, April 1, 4, 5, 6, 7, 8, 11, 12; 1949: December 5.
Present: Kerwin, Rand, Kellock, Estey and Locke JJ.
ON APPEAL FROM THE EXCHEQUER COURT OF CANADA
Patents—Infringement—Validity of Patent—Use of xanthates in froth-flotation concentration of ores—To determine whether a patent "correctly and fully describes the invention" the specification must be read as a whole—Claims which include substances harmful to the process are invalid—The Patent Act, 1923, S. of C., c. 23, ss. 7(1), 14(1)—The Patent Act, 1935, S. of C., c. 32, s. 61(1) (a).
The respondent claimed a patent for improvements in the froth-flotation concentration of ores by the use of certain sulphur derivatives of carbonic acid and sued the appellant for infringement. The appellant contended that the patent as a whole was invalid in that it did not correctly and, fully disclose the invention and that of the claims sued on, 6, 7 and 9 were too broad and 8 was not infringed. The disclosure set forth that certain sulphur derivatives of carbonic acid had been found to increase greatly the efficiency of the froth-flotation process when used with frothing agents and paragraph 4 read: "The invention is herein disclosed in some detail as carried out with salts of the sulphur derivatives of carbonic acid containing an organic radical, such as an alkyl radical and known as xanthates, as the new substance. These form anions and cations in solution."
Claim 6 read: "The process of concentrating ores which consists in agitating a suitable pulp or an ore with a mineral-frothing agent and an alkaline xanthate adapted to co-operate with the mineral-frothing agent." The improvement in the concentration as set out in claim 7 was to be "in the presence of a xanthate"; in claim 8, "in the presence of potassium xanthate"; and in claim 9, "in the presence of xanthate and a frothing agent."
Held: (Kerwin J. dissenting), that in determining whether a patent "correctly and fully describes the invention," the Specification, including the disclosures and claims, is to be read as a whole.
Held: also that claims 6, 7, 8 and 9 were invalid since they included substances i.e., xanthates, admittedly harmful to the process.
Per: Kerwin J., dissenting,—"Xanthate" as used in claim 9 must be read as limited by the definition in the disclosures, and as it is a technical word for which there is no precise meaning, the inventor supplied one in paragraph 4 of the disclosures—the term thus limited did not include cellulose xanthates and heavy metal xanthates. APPEAL from a judgment of the Exchequer Court, Thorson J., President, 1 holding that claim 9 of Letters Patent No. 247,576 was valid and had been infringed by the appellant.
P. C. Finlay K.C. and Christopher Robinson for the appellant.
E. G. Gowling K.C. and Cuthbert Scott and J. C. Osborne for the respondent.
Kerwin J.: (dissenting) The defendant in this action, Noranda Mines Limited, appeals against a judgment of the Exchequer Court 2 declaring that claim 9 of Canadian Letters Patent of Invention dated March 10, 1925, was valid and had been infringed by the appellant and ordering the usual consequential relief. The letters patent were issued as the result of an application filed October 23, 1924, for an invention of Cornelius H. Keller relating to Froth Flotation Concentrates of Ores. The respondent is the plaintiff Minerals Separation North American Corporation to whom Keller assigned all his right, title and interest in and to the invention, and to whom the letters patent were issued. Claims 6, 7 and 8 were also in suit but the trial judge, the President of the Exchequer Court, decided that the first of these was void for avoidable obscurity and that, in view of his conclusion as to claim 9, it was unnecessary to deal with 7 and 8. The appellant admits infringement on claim 9 and as I have come to the conclusion that it is valid, no opinion is expressed as to the other three.
Froth flotation is a method of treating an ore so as to separate the gangue from the values, and which method reduces the bulk of material that has to be subsequently smelted to obtain the desired metal. The operation is accomplished by the addition of a frothing agent to the pulp to which the ore had already been reduced and by such a violent agitation of the pulp that, at the top, a voluminous froth is formed, having the property of tending to cause the values to adhere to the bubbles as they rise through the pulp. The froth is removed and, after the required number of treatments the minerals contained therein are known as the concentrate. For my purpose the process may be thus baldly stated because although it was fully developed in the evidence and is set forth in detail in the reasons for the judgment appealed from, there is no dispute between the parties as to its existence in that form at the earliest time of any importance in the litigation, that is March, 1915, which is relied upon by the appellant as being the time when the use of xanthates in froth flotation concentration of ores was known by one R. B. Martin. In fact the first ground of appeal of the appellant is that the President was in error in holding the contrary. Before proceeding, the other three grounds of alleged error may be stated:—
2. In holding that the specification of the patent in suit described the invention in the manner required by the statute;
3. In holding that claim 9 was limited by the disclosure to a certain kind of xanthates;
4. In holding that the disclosure was limited to a certain kind of xanthates which did not include cellulose xanthate and heavy metal xanthates.
It will be convenient to examine the last three of these allegations before turning to the first but attention should now be directed to subsection 1 of section 7 and subsection 1 of section 14, of the Patent Act, chapter 23 of the 1923 Canadian Statutes, which was the enactment in force at the time of the application for, and granting of, the patent in suit. These enactments are as follows:—
7. (1) Any person who has invented any new and useful art, process, machine, manufacture or composition of matter, or any new and useful improvements thereof, not known or used by others before his invention thereof and not patented or described in any printed publication in this or any foreign country more than two years prior to his application and not in public use or on sale in this country for more than two years prior to his application may, on a petition to that effect, presented to the Commissioner, and on compliance with the other requirements of this Act, obtain a patent granting to such person an exclusive property in such invention.
14. (1) The specification shall correctly and fully describe the invention and its operation or use as contemplated by the inventor. It shall set forth clearly the various steps in a process, or the method of constructing, making or compounding, a machine, manufacture, or composition of matter. It shall end with a claim or claims stating distinctly the things or combinations which the applicant regards as new and in which he claims an exclusive property and privilege. It is upon subsection 1 of section 14 that the appellant relies in connection with its last three submissions and I therefore refer immediately to the disclosure. Paragraphs 2 to 7 inclusive thereof read:—
2. The invention relates to the froth-flotation concentration of ores, and is herein described as applied to the concentration of certain ores with mineral-frothing agents in the presence of certain organic compounds containing sulphur.
3. It has been found that certain sulphur derivatives of carbonic acid greatly increase the efficiency of the froth-flotation process when used in connection with mineral-frothing agents. The increased efficiency shows itself sometimes in markedly better recoveries, sometimes in effecting the usual recoveries with greatly reduced quantities of the usual mineral-frothing agents, and sometimes in greatly reducing the time needed for agitation to produce the desired recoveries.
4. The invention is herein disclosed in some detail as carried out with salts of the sulphur derivatives of carbonic acid containing an organic radical, such as an alkyl radical and known as xanthates, as the new substance. These form anions and cations in solution. Excellent results were also obtained by agitating ore pulps with the complex mixture produced when 33 per cent of pine oil was incorporated with an alcoholic solution of potassium hydrate, and xanthates or analogous substances were produced by adding carbon disulphide to this mixture.
5. The galena-bearing froth obtained with xanthates or analogous substances used at the rate of 0.2 pounds per ton of ore had a characteristic bright sheen, like a plumbago-bearing froth, and seemed to make a more coherent froth than when other materials were used on the same ore.
6. In general the substances referred to are not mineral-frothing agents,—producing only a slight scum, and some evanescent frothy bubbles, when subjected to agitation which would produce mineral-bearing froth on an ore pulp in the presence of a mineral-frothing agent. The substances are effective in enabling a selective flotation of lead and zinc; and cause uncombined silver, if present, to tend to go into the lead concentrate rather than with the zinc, where these are separated in separate concentrates. Usually pre-agitation is unnecessary, the brightening and other effects seeming to be practically instantaneous. The pulps may be either acid, alkaline or neutral according to circumstances.
7. Two sticks of caustic potash weighing perhaps 15 grams were partly immersed in about 80 cc. of commercial carbon disulphide and kept for about ten days in a closed bottle containing some air in the warm region of the laboraotry where were the hot plates used for drying. These eventually yielded a yellow or orange salt which was used with pine oil at the rate of approximately half a pound to a ton of ore in concentrating Hibernia ore from Timber Butte Mining Company. The test was with a neutral pulp, and the concentrates were seen to be clean with brightened lead sulphide particles.
Paragraph 8 states that for laboratory purposes potassium xanthate was prepared in the manner described and the subsequent paragraphs set forth certain tests, and the specification ends with eleven claims, of which the ninth only need be noticed:—
9. The improvement in the concentration of minerals by flotation which comprises subjecting the mineral in the form of a non-acid pulp to a flotation operation in the presence of a xanthate and a frothing agent.
In its attack the appellant has sought to place each of the paragraphs of the disclosure set out above in a straight jacket and by a meticulous examination of every word has endeavoured to show that Keller never put his finger on what he had discovered. That this is not a proper way to read the specification is made clear by a number of authorities, to one only of which is it necessary to refer. In Smith Incubator Co. v. Seiling 3 Chief Justice Duff states at 255:—
It is now. settled law that, for the purpose of ascertaining the meaning of the claims, the language in which they are expressed must be read in light of the specification as a whole, but it is by the effect of the language employed in the claims themselves, interpreted with such aid as may properly be derived from the other parts of the specification, that the scope of the monopoly is to be determined.
And at page 260, the present Chief Justice notes:—
As often observed, of course, the claims must be construed in the light of the rest of the specification; and that is to say, that the specification must be considered in order to assist in comprehending and construing the meaning—and possibly the special meaning—in which the words or the expressions contained in the claims are used.
In accordance with this principle, "xanthate" as used in claim 9, must be read as limited by the definition in the disclosure. This is not inconsistent with the decision of this Court in B.V.D. Company Limited v. Canadian Celanese 4 as xanthate is a technical chemical word for which there is no precise meaning and, therefore, the inventor supplied one in paragraph 4 of this disclosure. I agree that the words "such as" mean "of the type of". So read, Keller has made it clear to any one versed in the art that his invention consists of a new and useful improvement in froth flotation concentration of ores by the use of a mineral frothing agent with sulphur derivatives of carbonic acid containing an organic radical of the type of an alkyl radical which forms anions and cations in solution. Without detailing the evidence which appears in the President's reasons, I may state that I am satisfied that Keller's disclosure was limited to a certain kind of xanthates, which did not include cellulose xanthates and heavy metal xanthates.
I now turn to the first argument of the appellant that the use of xanthates in flotation was known in 1915 by Martin and that, therefore, Keller had not, in compliance with subsection 1 of section 7 of the Patent Act, invented any new and useful process not known by others before his invention. Martin was not called as a witness. He had been engaged by the respondent's predecessor in March, 1915, under an employment agreement, and by another agreement of the same date had given an option to a related English company for the purchase, subject to a shop right to Utah Copper Company, of all inventions previously made by him relating to the treatment of ores and to flotation concentrates and reagents. On the same day, Martin disclosed his alleged inventions to Higgins, the chief metallurgist for the respondent's predecessor. Among these was the only one requiring mention, "NATROLA", the name he had used at Utah Copper Company for a composition he later called "STANOL". At the trial, Higgins said Martin had been provided with laboratory accommodation, chemicals and ores, and that he had supervised Martin's work but that STANOL had been found by Higgins, Martin, and a third party to be of no use. Later, at Higgin's suggestion, Martin incorporated in a document dated August 15, 1915, and known as Bulletin 2, descriptions of his flotation reagents, including Stanol. Applications for patents covering other alleged inventions of Martin were prepared and according to the testimony of Mr. Williams, the respondent's patent attorney, they represented all that Martin had succeeded in demonstrating to be of any value of the inventions brought by him to his employer. Bulletin 2 was discussed between Higgins and Martin when the former found that there were so many formulae in the document that he concluded that they could not all be equally effective and he asked Martin to put the best of each one of them in a book of reference. Some time before October 21, 1915, this book was prepared and handed to Higgins and in it are set out certain notations showing what was most useful in each of the preparations contained in Bulletin 2. This was followed by Bulletin 3 in which STANOL is not mentioned. On October 22, 1915, Bulletin 4 was delivered by Martin to Higgins and on page 9 is mentioned "STANOL" and stated that it was not satisfactory on ore at Anaconda Mine. Bulletin 4 is the last one in which mention is made of STANOL notwithstanding that Martin prepared and delivered eighty-eight bulletins in all. Although applications were prepared for KOTRIX and certain reconstructed oils which had been disclosed by Martin, he and Higgins decided that there was nothing of value in STANOL to patent. It appears that shortly after the issue of the Keller patent in the United States, Martin resigned his position with the respondent and subsequently was instrumental in having declared an interference between the Keller United States patent and Martin's own application for a patent. This interference was dissolved without a determination of the question of priority.
Nowhere did Martin claim that STANOL was xanthate. He was thinking of STANOL only and while he theorized as to there being some xanthate in it and that it should be effective in flotations, the evidence all leads to the conclusion that he did not know the value or use of xanthate as such; that is, he did not know the invention that Keller later made. It should be added that there is no suggestion that Keller ever saw Martin's bulletins or books. This makes it unnecessary to consider the respondent's argument that even if Martin did know, section 61(1) (a) of the present Patent Act, 1935, a 32, although enacted in 1932 by c. 21, sec. 4 (after the patent in suit was issued) applies so as to render such knowledge unavailing unless Martin had disclosed or used his process in such manner that it had become available to the public.
The appeal should be dismissed with costs.
The judgment of Rand and Locke JJ. was delivered by:—
Rand, J.:—The first objection raised by the validity of the patent is that the inventor, in the specification, has failed to satisfy the requirement of the statute that he describe his invention correctly and fully. Both at the trial and before us the defendant pressed the question, what is the invention? And to deal with that initial challenge adequately a statement of the main facts must be given. The invention is stated to be an improvement in a process known as the froth flotation of minerals, a method of separating them which in its modern form dates from the year 1905. These minerals are chemical compounds containing metals such as gold, silver, copper, lead, etc.; and they are found generally in a mixture with other substances, chiefly silicas, called an ore body. The minerals may be thickly or thinly scattered throughout the ore; but their extraction from the mixture is a preliminary to the direct recovery of the metal from the compound in which it appears.
The flotation process consists, first of crushing and grinding the ore to varying degrees of fineness: the material is then thoroughly mixed with water into what is called a pulp: an oil or similar substance is added: air is introduced, and the whole well agitated. Masses of bubbles are formed, apparently with an oily film, which, laden with mineral particles, rise to the top in a dark scum called the concentrate. This scum is collected, the froth matter is driven off, and the residue of mineral is then ready for the smelter.
The oil or other substance added is primarily a frothing agent: but it has also more or less a collecting function, that is, it produces an attraction between the air bubbles and the mineral particles which causes the latter to cling to the former. The theory of this attraction seems not to be agreed upon, nor whether the emulsified oil in any degree films the particles. But I infer that it is a real attraction, probably of an electro-magnetic nature, and is not merely a mechanical involvement of the particles in the surface tension of the bubbles. The attraction may also be selective: that is, the copper, say, may be caught up in priority to the lead. Some agents are more effective in producing froth than collecting the mineral while others have a converse action: and a combination of two or even more may be used. So many factors of difference in the minerals and in the ores are found, that each mine tends to work out its own best method; changes in the chemical composition may take place more or less constantly, both slowly and rapidly, and local adaptation may become a factor in good operation. For instance, mineral may oxi- dize. Now oxide minerals, in which an oxide of the metal sought predominates, cannot directly be recovered in flotation: the bubbles do not collect the particles. In sulphide minerals, on the other hand, they do. Oxides are therefore washed or filmed with a sulphidizing agent and they then are amenable. The choice of agents to be used may thus, by similar and other conditions, be influenced.
The search then became one for more effective collector agents, including agents for sulphidizing, substances that would, at the cheapest cost, gather to the concentrate the greatest quantity of values, or minerals, and the least of the waste or gangue: and the whole field of organic and inorganic chemistry was opened to the exploration.
In this state of things, the scientists of the respondent took up the hunt. In 1922, September 19, one of them, a chemist named Keller, in search of a sulphidiser, issued a direction to his associate in metallurgy to test a salt known as potassium xanthate for that purpose. In the course of the next year a great many experiments with xanthate and similar substances were carried out in the company's laboratories at San Francisco and New York. It was discovered that certain xanthates, although not sulphidizing agents, did produce a remarkable increase in the flotation efficacy of frothing or collecting agents. They were not capable of producing froth and did not, apparently, react through coating the particles of mineral. Their property of enhancing the process was demonstrated in March, 1923; and after continuing tests and the exploration of peripheral areas throughout the summer and autumn, application for a patent was made in the U.S.A. on October 21, 1923.
Since the discovered salts have neither frothing nor sulphidizing powers, they are not directly effective on oxide ores until first sulphidized, and they must be combined with a frothing agent: their role is to influence favourably the process as it was carried on with oils and other substances at the time of the invention. They are therefore new factors whose effect is made upon the existing process, in which they appear to play a part analogous to that of a catalytic agent.
Now it is obvious that in the field of chemistry family relationship in compounds is likely to be characterized by similar significant reaction results; and that a xanthate has such modifying powers leads at once to the notion of a chemical group which, possessing certain characteristic qualities, may be efficacious in producing the same effects. So it happened with Keller. Having made an important discovery, he set about to distribute the field of such agents not only as a contribution to the operation but also to protect his invention against encroachment. The invention became therefore the discovery of a series of modifiers and the initial question raised is whether there has been a sufficient description of that series. In such a, case an inventor cannot be called on to investigate and to name every possible substance individually of the group; he may do that by a description and that description may be of attributes or by classification.
The argument tended to assume that the "correct and full" description required by section 14 of chapter 23 of the Patent Act, 1923 must be in what has been called the narrative portion of the specification. But the statute makes no such provision; the specification is to end with the claims, but it is in the specification that the description must be given: and to the whole of it we are entitled to look to ascertain what the invention is. The language of Duff C.J. in Smith Incubator Co v. Seiling, 5 at p. 257, in which he speaks of the specification "as a whole", seems to me to have been carefully phrased to avoid the restrictive interpretation suggested.
The specification recites that "it has been found that certain sulphur derivatives of carbonic acid" are effective for the purposes of flotation. It then proceeds to reduce this general statement to defined particulars by furnishing examples of derivatives which embody the special property, by indicating certain characteristics and lastly by delimiting, in the claims, the boundaries, within the field of the derivatives, of the group for which the inventor asserts monopoly. The introductory sentence to the claims, "Having described certain embodiments of the invention, what is claimed is", clearly, I think, relates the claims to the description as well as the delineation of the exclusive field. What the disclosure lacks to a full description is the completion of enumeration; at this point description has become enumeration, and that is furnished by the claims. I take the disclosure to imply in fact that the invention consists of those sulphur derivatives of carbonic acid which are described or defined in the claims. So far as a claim may include, for instance, a useless or an antagonistic substance, it is, as a definition of the monopoly, defective, but its descriptive function remains. The only question then is whether when the description contains a substance of no value or use the patent ipso facto is invalid as not specifying the invention correctly and fully. The special circumstance here is that the invention is a distributive discovery; (a), (b), (c) and (d) are asserted individually and severally; the first three have in fact been invented and are correctly and fully described; but the inventor has also described as invention, (d), which he has not invented. Assuming a claim which does not include (d), it is as if the inventor had declared, I assert I have also invented (d) but I do not claim it. Only if we treat the invention as being of the group as an entirety, can it be said that the description is not correct; but that is not what the specification here intends. The substances are to be viewed as quasi-independent inventions but by the necessities of the case they can distributively be made the subject of a single patent.
The invention is therefore the use in flotation of those substances taken distributively which are sulphur derivatives and which are of such nature or characteristics, are so combined, and react in such conditions as are expressed in the specification as a whole. To require the full detailed description to be given in the so-called narrative would necessitate a virtual repetition of the claims. Taking the specification in its totality, Keller has, I think, met the requirement of the statute: no competent metallurgist would have any difficulty in grasping the discovery in all its essentials.
Against this conception, it is said that the expression "sulphur derivatives of carbonic acid" is ambiguous, on which there would be wide divergencies of opinion in metallurgists or chemists. But it is agreed by Dr. Purves, for the appellant, that a sulphur derivative is one in which the oxygen of the formula H2CO3 is replaced by sulphur. The initial replacements would result in H2CO2S, H2COS2 and H2CS3, mono-, di-, and tri-thio-carbonates. Dr. Purves, however, in a chart of resultant combinations, in the mono- and di-groups substituted chlorine or an ammonium radical for OH: in doing that he violated, I think, the primary premise of sulphur substitution for the oxygen. In this I accept the opinion of Higgins, the chief metallurgist of the respondent, that "derivative" means exactly what it says, and that the introduction of CI and NH2, though it does produce a derivative containing sulphur, does not produce a sulphur derivative of carbonic acid; it would properly be called a chlorine or other derivative of a sulphur derivative; but to that the statement of the discovery does not extend.
The invention was one of great value to the mining industry and brought in a group of agents of which there had been no previous knowledge or experience. It was not only natural but legitimate that the inventor should have endeavoured to protect his discovery. Precise description in such an uncharted field is hedged with difficulty; and although overreaching must draw its penalty, we are not called upon to employ microscopic means of discovering it nor to insist upon a pedantic accuracy to satisfy a formal symmetry.
A great deal of the evidence was taken up with matter arising out of the 4th paragraph of the specification which reads:—
The invention is herein disclosed in some detail as carried out with salts of the sulphur derivatives of carbonic acid containing an organic radical, such as an alkyl radical and known as xanthates, as the new substance. These form anions and cations in solution. Excellent results were also obtained by agitating ore pulps with the complex mixture produced when 33 per cent of pine oil was incorporated with an alcoholic solution of potassium hydrate, and xanthates or analogous substances were produced by adding carbon disulphide to this mixture.
The respondent took the position that here was an exclusive description of xanthate for the purposes of the specification; that the xanthates intended to be denoted by that term were those containing an alkyl radical, which in solution formed anions and cations. These compounds, it may be stated, are salts of xanthic acid. That restrictive definition was considered necessary seemingly to support claim 9 which speaks of "a xanthate", by excluding certain xanthates which admittedly are of no value, such as cellulose and certain of the heavy metal compounds. This re- duction of the discovery to special xanthates and "similar substances" mentioned in paragraphs 4 and 7 appears to me to be incompatible with the plain meaning of the language of the paragraphs as well as of the specification generally. What the narrative does is to furnish the circumstances and results in tests of certain "embodiments" of the invention, or, as one might say, of certain members of the group discovered. The reference may be taken as limited to such xanthates; but they are named only as illustrative examples: they, only, are disclosed in some detail; but that the language is intended to furnish a conventional meaning of xanthate to be carried forward into the claims is a conclusion which I am quite unable to draw.
The claims which the defendant is charged with infringing are numbers 6, 7, 8 and 9. The first, 6, is as follows:—
The process of concentrating ores which consists in agitating a suitable pulp of an ore with a mineral-frothing agent and an alkaline xanthate adapted to co-operate with the mineral-frothing agent to produce by the action of both a mineral-bearing froth containing a large proportion of a mineral of the ore, said agitation being so conducted as to form such a froth, and separating the froth.
It was attacked as ambiguous in the expression "alkaline xanthate". Admittedly xanthates are neither alkaline nor acid: they are neutral; and the adjective, as every competent metallurgist would know, cannot be taken to indicate such a characteristic of the substance. Nor do I think it can be taken to refer to the condition of the pulp. But, in some sense it does clearly qualify xanthate and I find no difficulty in satisfying myself in what that lies. Throughout the disclosure it appears that xanthates of potassium and sodium were used exclusively in the experiments. These are two alkali metals which in the standard formula for xanthate replace the hydrogen atom associated with sulphur. The disclosure also describes 'how these xanthates were made by the inventor, which was by first dissolving the hydrate of the one or the other in ethyl alcohol and then adding carbon disulphide. From these facts and the somewhat free and imprecisely adapted use of adjectival language by chemists, as well as the general knowledge of the chemistry of xanthates, I think it a reasonable inference that the language is intended to describe xanthates in which the metal or radical which replaces the hydrogen atom is that which comes from an alkali, those in the making of which an alkali is used. Several alternatives were suggested. The meaning attributed by the respondent was alkali metals, which are those present in alkalies: the appellant suggested, in addition, alkaline earths which are earths, i.e. oxides, of chlorine and certain allied elements, and which exhibit properties midway between alkalies and earths: but I am unable to take the word to relate to either of these classes. Claim 5, in specifying an "alkali metal" salt, seems to conclude the question against the first; and the second falls through its own remoteness,
It was contended by Mr. Robinson that, on the respondent's interpretation, the inclusion of ammonium xanthate invalidated the claim because that substance was of no value in flotation. The evidence relied on is the report of Keller in which he describes the combination of ammonium hydrate with alcohol and carbon disulphide to produce what he took to be xanthate. But both Higgins and Dr. Purves agree that ammonium xanthate cannot be so produced and that Keller was wrong in his chemistry. Whatever the product his mixture gave him, whether good or bad for his purpose, it was not xanthate; and ammonium xanthate has not been shown to be of no utility.
But it would appear that whether we take the expression to signify alkali or alkali metal, the same objection arises. The evidence discloses that cellulose xanthate is a product from ingredients of which the alkali, sodium hydrate, is one; it is then a xanthate embraced within both meanings; and since admittedly it is harmful to the process, the claim cannot stand.
But with this, the language "with a mineral-frothing agent and an alkaline xanthate adapted to co-operate with the mineral-frothing agent to produce by the action of both a mineral-bearing froth containing a large proportion of a mineral of the ore" must be considered. At trial, the appellant challenged this language as insufficient in not specifying which xanthates were "adapted" and which not. In this interpretation "adapted" relates to the properties of the xanthate necessary to co-operative action, and its effect would be that it would restrict xanthates to those that could be successfully used. Mr. Gowling, in his factum, states that "it simply means that the purpose of mixing the two substances is to enable them to co-operate together to give the desired result." I must confess to a difficulty in appreciating the sense intended to be conveyed by this but, in my opinion, in any admissible sense the clause cannot be taken validly to restrict the scope of "alkaline xanthate" to those that will co-operate, and the clause does not, therefore, affect the conclusion otherwise reached.
The second claim, 7, reads:—
The improvement in the concentration of minerals by flotation which comprises subjecting the mineral in the form of a non-acid pulp to a flotation operation in the presence of a xanthate.
This is met by the formidable objection that "a xanthate" means any xanthate including cellulose xanthate. It may be convenient to state here that "cellulose" xanthate is a description in terms of the organic radical used; but xanthates are also known in terms of their metal or of both the metal and radical. The only answer to this is the special interpretation given paragraph 4 with which I have already dealt. The common knowledge contained in. the working chemistry dictionaries in 1923 extended to a great many xanthates besides those of soluble metals or alkyl radicals. They had become in fact known to Keller. For these as well as the reasons already given, I must give the language its ordinary meaning and hold the claim invalid.
A second objection is that the claim extends to the use of xanthate without a frothing agent. If it stood alone, I should be disposed to interpret "flotation operation" as including a frothing function. But the express mention of a "frothing agent" in claim 9 in collocation with "flotation operation" implies there either some special conjunction with the xanthate or that two frothing agents are contemplated, or that "flotation operation" is not intended to embrace frothing. The duty of an inventor is to define intelligibly and consistently the boundaries of his exclusive area, and it would be doing violence to this requirement to accept either of the first two suggested meanings; I must then take it that where a frothing agent is not mentioned it is intended to be excluded as a requirement. On this ground, also, the claim fails.
Claim 8 is as follows:—
The improvement in the concentration of minerals by flotation which comprises subjecting the mineral in the form of a non-acid pulp to a flotation operation in the presence of potassium xanthate. It raises the same question of frothing agent just considered and for the same reason it is defective.
It was urged that the appellant did not use potassium xanthate within six years preceding the commencement of action. The respondent's answer was both that Exhibit M2 shows that use and that sodium xanthate is a chemical equivalent. The contradiction arises from the fact that the ' defendant takes potassium xanthate in the claim to mean potassium ethyl xanthate and the respondent that it covers potassium xanthate with any alkyl radical. Paragraph 8 of the specification sets out the method followed by Keller to make potassium xanthate and the ingredients used show that he made potassium ethyl xanthate. But that was for laboratory purposes only and there is no implication that it is the only potassium xanthate or that for the purposes of the specification potassium xanthate means that with the ethyl radical. Both amyl and hexyl radicals are mentioned in Exhibit No. 6 listing the xanthates made before 1923. Notwithstanding the evidence of Higgins, that, in common parlance among metallurgists, in the absence of reference to the radical, ethyl is understood, I think the respondents are right in their interpretation.
This in turn raises the question of potassium cellulose xanthate. The metal used in cellulose xanthate, in the manufacture of rayon, is sodium: but the evidence of Bennett is that potassium xanthate of cellulose has the same effect on flotation as the sodium compound, a conclusion which would follow from the fact, agreed upon, that in these compounds the two metals are interchangeable.
Assuming the expression signifies ethyl xanthate, the contention that sodium is, for this purpose, an equivalent must be considered. Both sodium and potassium xanthates, presumably ethyl, are disclosed as having been made and tested and found beneficial to flotation. Potassium was evidently more fully explored than sodium although the latter would appear to be the cheaper product. Both were thought, no doubt, to be protected under claim 7: and we are entitled to ask, why, then, the special claim for the one and not the other. It may be that potassium xanthate was looked upon as the central and basic discovery which would carry with it any such equivalent. But that is a speculation which I do not feel at liberty to act upon. An equivalent is a known substitute means to a certain end; but here sodium xanthate is known as a modifying agent only as it has been discovered as part of the invention. To select one of two substances so discovered is impliedly to exclude the other: otherwise it would be to patent the invented substance not directly but as an equivalent; but the specification makes it quite clear that these two substances are not being dealt with in that manner.
The claim, then, is too broad and fails.
The last is 9:—
The improvement in the concentration of minerals by flotation which comprises subjecting the mineral in the form of a non-acid pulp to a flotation operation in the presence of a xanthate and a frothing agent.
This the President held valid. He accepted the contention that paragraph 4 defines and limits