of the digester, and, by its action thereon, injuring it. The means devised or used to accomplish this object or purpose were "a continuous lining or coat, B, of acid-resisting material" applied to the shell in "a plastic condition" and "capable of being made plastic and adhesive to the shell," and, when necessary, the interior lining of tiles to prevent "the friction of the mass of pulp within the digester" from "mechanically" wearing "away the lining constructed as described." The patent is broad, in that any material having these qualities may be used, but narrow, in that this lining or coat complete must be "continuous" and must be composed of materials having the qualities described, viz., "acid-resisting," "adhesive," and "plastic when applied." The claims are two in number, and read as follows:

"(1) The improved pulp-digester herein described, having an outer shell, A, and a continuous lining or coat, B, of cement, as described, applied to the interior of the said shell, for the purpose set forth.

"(2) The improved pulp-digester herein described, having an outer shell, A, a continuous lining or coat, B, of cement, substantially as described, applied to the interior of the said shell, and an interior lining of tiles, C, all substantially as set forth."

The elements of claim 1 are, first, the outer shell, conceded to be old in the prior art; and, second, (a) the continuous acid-resisting lining described; (b) such lining applied to the interior of the shell and adhering thereto, made a matter of necessity; (c) all to serve the purposes "set forth."

The elements of claim 2 are, first, the pulp-digester described, having (a) the outer shell; and (b) the continuous acid-resisting lining or coat of cement applied to the interior of the shell and adhering thereto, made a matter of necessity; and, second, an interior lining of tiles as described. Claim 2 adds the element of "an interior lining of tiles." These claims are, of course, limited to a "continuous coating" made of "plastic material," when applied, and also "acid-resisting" material. But the patent contains other limitations. He expressly says:

"I am aware of the use heretofore of a digester-lining comprising a layer or coat of masonry or brickwork laid in cement, and make no claim thereto."

This necessarily excludes all linings made of stone and brick or tiles laid in cement whether that cement be Portland, or some other, acidresisting, or some other, adhesive, or some other, plastic when applied, or otherwise. And it would exclude such a lining of masonry plastered over on one or both sides with the same cement in which laid for such a plastering over of masonry is a common expedient, and has been for centuries. This is a matter of which courts will take notice. The patent in suit goes on to say:

"Such linings I believe to be objectionable, in that they are heavy and require in many forms of digester special forms of tile or brick to be constructed to fit various portions of the digester-shell, especially around openings, &c. Furthermore, they are expensive by reason of requiring to be laid with great care and skill to prevent defective joints through which leakage may take place. On the other hand, in a digester embodying my improvements the lining may be applied rapidly and easily, and may be composed of material not necessarily expensive. Again, it has been customary to supplement the brick or tile linings heretofore in use with a lining of sheet lead interposed between

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the brick or tile lining and the digester-shell. This feature may be entirely dispensed with where my improvement is adopted.

"I mean to be understood that the digester-linings comprising a layer or coat of masonry or brickwork laid in cement, to which I have just referred, have always been, so far as I know, supplemented by a lining of sheet lead interposed between the brick or tile lining and the digester shell. The construction I refer to as old is that shown and described in the United States letters patent to Mitscherlich, No. 284,319, dated September 4, 1883, in which the digester-shell is protected from the acid solution by a sheet-lead lining, and the only apparent use of the brick or tile lining in addition to the lead lining is to protect the latter from extreme high temperatures.

"I am also aware of the United States patent to Reynolds, No. 423,531, dated March 18, 1890, which describes a digester having a metal shell and an interior structure of brick with leaded joints, a fluid-chamber or space being left be tween the shell and the brick structure. The patent contemplates the filling of this chamber with fluid-such as air, water, or steam under pressure-in excess of that employed in digesting the pulp, so as thereby to prevent the brick structure from disintegration under pressure from within outward. It also states that the inner surface of the shell may be coated with a paste of red lead, and thus protected against possible injury by acid leaking through the brickwork. Such a structure I consider merely a modification of the Mitscherlich by the addition thereto of the pressure-chamber, the lead paste of Reynolds being the equivalent of the lead sheet of Mitscherlich.

"I am aware that cement linings have been employed in various open vessels used for heating acid solutions; but in such open vessels the temperature never exceeds 212°. In digesting wood pulp by the sulphite process, the contents of the digester are under very high steam pressure, sometimes as much as 100 pounds to the square inch, and I believe it to have been unknown until demonstrated by me that a cement lining would stop the passage of the acid solution to the digester-shell, notwithstanding this high pressure and temperature."

It will be noted that he states, in substance and effect, that in the prior art brickwork or masonry linings laid in cement are common, not built directly against the shell, but having interposed between then and the shell linings of sheet lead. This lead lining was to prevent injury to the shell by preventing the acids contained in the pulp solution from reaching it. This lead would not, probably, adhere to the shell. But that fact is immaterial as it would retain its place held by the shell on the one side, and the masonry lining on the other. Hence, in the patent in suit, so far as claim 2 is concerned, which has the masonry or tile lining in addition to the coating of acid-resisting material, we have a mere substitution in the patent in suit of an acid-resisting adhesive cement coating, plastic when applied, for the acid-resisting lead coating or lining, not necessarily adhesive to the shell, of the prior art. It is true that the patentee says the use of the brick or masonry in addition to the lead lining was to protect the latter from excessive high temperatures while his use of the tile or masonry lining, in addition to the lining of acid-resisting material, is to prevent wear of the latter by the friction of the mass of pulp in the digester. But, later in the specifications, the patent speaks of this great heat and pressure, and, taking the specifications altogether, they ascribe to the cement lining precisely the same function or office performed by the lead. lining of the prior art. The prior art also had, and this is stated in the patent in suit, the metal shell and an interior lining of brick with leaded joints and a fluid space or chamber between it and the shell,

filled with air, water, or steam under pressure. This, says the patentee, was to prevent disintegration of the brick lining under pressure from within outward. In fact, it was also to prevent injury to the shell by keeping the acid from it.

But the patent in suit also says, referring to the prior art, Reynolds patent of March 18, 1890, No. 423,531:

"It [the prior patent] also states that the inner surface of the shell may be coated with a paste of red lead, and thus protected against possible injury by acid leaking through the brickwork."

The patentee of the patent in suit also says:

"Such a structure I consider merely a modification of the Mitscherlich [a prior patent] by the addition thereto of the pressure chamber, the lead paste of Reynolds being the equivalent of the lead sheet of Mitscherlich."

But the continuous sheet of sheet lead acid-resisting lining of Mitscherlich was to prevent injury to the digester by the solution employed; that is, to prevent the acid of the solution from reaching the shell. The object of the Reynolds patent in using his continuous coating of a paste of red lead, which is plastic when applied, and also adhesive and acid-resisting, and applying it in a continuous coating on and to the inner side of the digester shell, was precisely the same; that is, to prevent injury to the digester, the shell thereof, by the acids in the solution employed and contained in the mass of pulp. The patent in suit so states. And this is the precise object and purpose of the patent in suit. The object and purpose of each of the two patents referred to in the patent in suit, and which show the prior art, and of the patent in suit are precisely the same. So far as claim 2 of the patent in suit is concerned, the only difference between it and the Reynolds patent is that Reynolds used a coating or lining of red lead, a plastic material, adhesive and plastic when applied, and also acidresisting, to prevent injury to the shell, by keeping the acids contained in the mass of pulp being digested, from such shell; while the Russell patent in suit uses "any material or mixture of materials which are acid-resisting and capable of being made plastic and adhesive to the shell of the digester, and so compact as to prevent the acid solution from reaching the iron shell in consequence of the high steam pressure required in practice." Reynolds used red lead which answered all of these conditions. He used the interior lining of masonry also. The patent in suit, in claim 1, does not specify the masonry lining, but claim 2 does. The patent in suit is a mere extension of the Reynolds patent by including, not additional means of a new nature, action, or composition, or new means operating differently, but means of the same composition having the same qualities operating in the same way, and which will answer the same purpose, produce the same result, or attain the same object. In short his entire conception of means to attain a wellknown and desired result is not that an adhesive, plastic (when applied), acid-resisting material will attain that result under pressure and high temperature, for this he well knew as the prior art, which he in fact knew, taught him that; but that if one plastic, adhesive and acid-resisting material would do it any other would. Hence he tried and found that

Portland cement would do the work, and that any cement-like material having the necessary properties would. This everybody having practical common sense and any knowledge on the subject well knew. The prior art in digesters of this class taught that a firm, plastic (when applied), acid-resisting, cement-like and adhesive material, applied as a continuous coating to the interior of the shell of the digester, would prevent the acid from acting injuriously thereon. The patentee may have found some new substance possessing the required qualities, but his patent is not for such a discovery. That is not what he claims.

Was it invention to do this? Russell is not the author of the conception that such a material applied to the interior of the shell of a digester under high temperature and pressure will prevent injury to the digester or shell, but his predecessor in the art, Reynolds, was. And more, Reynolds put his conception to practical and successful use in a digester of this description under the conditions named. These substances suggested by the patent in suit for forming the lining are of the same kind and quality, and possess the same attributes or chemical qualities, so far as necessary for the use designed, as did the substance used by Reynolds. But more than this the patent says as already quoted:

"I am aware that cement linings have been employed in various open vessels used for heating acid solutions; but in such open vessels the temperature never exceeds 212°. In digesting wood pulp by the sulphite process the contents of the digester are under very high steam pressure, sometimes as much as one hundred pounds to the square inch, and I believe it to have been unknown until demonstrated by me that a cement lining would stop the passage of the acid solution to the digester shell, notwithstanding this high pressure and temperature."

Here is a statement in express terms that the prior art shows the use of cement linings for the same purpose in open vessels, and their well known adaptability and utility therein are admitted, but, he says, in such prior use the temperature did not exceed 212 degrees, whereas, in digesters for digesting wood pulp by the sulphite process, the contents are under a steam pressure sometimes as high as 100 pounds to the square inch. Then he says, and here if anywhere, is the conception:

"I believe it to have been unknown until demonstrated by me that a cement lining would stop the passage of the acid solution to the digester shell notwithstanding the high pressure and temperature."

This is a confession or concession that the prior art taught, as was the fact, that cement linings under some pressure, and at a temperature of 212 degrees, would stop the passage of the acid solution to the digester shell, and hence a concession that the prior art taught the utility and adaptability and efficiency of cement linings for preventing the acids in wood-pulp digester solutions from reaching the shells. All the Russell patent claims is the discovery that such linings were in fact efficient in closed vessels under a high steam pressure and temperature. In view of the prior art with which he is presumed to have been familiar, and with which he confesses himself to have been

conversant, all he had to do was to try. It was simply a test of how much heat and pressure it would require to force these acids through such cement linings. It was not a new conception or conception of new means, neither was it the use of new means, nor was it the use of old means in a new way to produce the desired result or a new result, or the old result in a better way. It was simply the use of old means in the old way to produce the old result, but under different not new conditions-conditions which differed in degree only. Any person skilled in the art possessing ordinary skill therein, would have apprehended and discovered all that the patent discloses. It would have occurred to any one that such was probably the fact, and merely testing was the proof and the result of the test constituted the discovery. No new quality or function in cement linings of this description was discovered or disclosed. There is no new adaptation, not even a use in a new place or under new conditions except as the conditions vary in pressure and temperature. Was this patentable invention?

I have studied with care and industry the cases where the validity of this patent in suit has been in question, and decided in the affirmative, but am unable to agree with the conclusions reached. They are, to my mind, based on the unfounded assumption that Russell discovered that cementitious linings would resist the acids contained in wood pulp when undergoing the digestive process under high pressure and temperature, and conceived the idea of a continuous coating of acid-resisting material, or that he conceived the idea of a continuous coating of acidresisting cementitious material as a substitute for the prior lead lining used in the same place for the same purpose.

In American Sulphite Pulp Co. v. Howland Falls Pulp Co., 80 Fed. 395, 399, 25 C. C. A. 500, the Circuit Court of Appeals. First Circuit, reversing Judge Putnam, said that Russell "conceived the idea of a seamless, homogeneous lining, to be composed of materials from which brick, tile, and artificial stone are made, which should be acid, resisting, and so far adhesive that it would attach to the shell and become a part of the structural formation, and so far cohesive, expansive, and resilient as to respond to the expensive and retractive force of the iron shell when subjected to the varying conditions of heat and cold. as was necessary in the process of cooking and curing the wood." This patent in suit shows on its face that he did nothing of the sort. He not only confesses therein that he did not, but, as stated, expressly says that what he has discovered is that these old and well-known cementitious acid-resisting linings will resist and prevent ("stop the passage" to use his own language) the penetration "of the acid solution to the digester shell notwithstanding this high pressure and temperature" which he has described as existing in a digester, where the sulphite process is used, and which is much greater than the temperature and pressure in the cementitious lined open vessels where these same cementitious linings had been commonly used for the same purpose and under the same conditions except as to degree of heat and pressure. Therefore, as stated, all he pretends to claim is the discovery that such cementitious linings had a greater acid-resisting power than the prior art had practically disclosed. It was not the conception or discovery