Statement of the case.-Keen's patent, A.D. 1863. A represents a vertical cylindrical boiler, which is mounted on supports, B, or on any other suitable frame. The upper part of the boiler is made conical, and is provided with an expansion chamber, C, through the aperture of which the boiler is charged, and which is closed by a cover, D, which is bolted steam-tight Statement of the case.-Keen's patent, A.D. 1868. to the same. The bottom of the boiler A, is made funnel-shaped, and ends in the centre in the discharge-pipe, E, which is closed by a piston or stop-cock, G. The latter is secured to the rod H, and can be opened or closed by means of the hand-wheel F, of the rod H, which passes through the stuffing-box I, and has its lower bearing on the bracket a. K represents two stirrers, the shafts of which run at their lower ends in the steps b, while their upper ends pass through the stuffing-boxes L, and are provided with pinions M, which are driven by suitable gearing. Statement of the case.-Keen's patent, A.D. 1863. The shafts of the stirrers, K, are provided on one side only with the horizontal stirring arms, which, when the boiler is to be charged are turned towards the periphery of the boiler, and are therefore not in the way of the material as it is thrown into the boiler. d represents a perforated plate, which is secured to the rod, N, and which rests on the brackets, g, of the expansionchamber, C. It is intended to press the material down and to keep it submerged in the fluid in which it is to be boiled. The plate, d, is prevented from rising by the upper end of the rod, N, being in contact with the lower face of the cover, D. O represents try-cocks, by which the material in the boiler can be tried, to what degree of perfection the stock is worked. The operation is as follows: The boiler being charged with the proper solution of caustic alkali or other suitable fluid, and with the material which is to be reduced to pulp, the plate d is placed upon it, and the cover G is screwed down tightly. The boiler A is then heated, either by a direct fire or by any other heating apparatus, and the mass in the boiler is boiled and stirred until thoroughly disintegrated. During this process the steam arising from the fluid rises through the perforated plate, d, and fills the expansion-chamber, C, whence it exerts a pressure upon the boiling mass in the boiler. When the stock has been reduced to the desired perfection, the stop-cock, G, is opened by means of the hand-wheel, E, and the entire mass is blown by the pressure of the steam in the expansion-chamber and boiler through the pipe, E, as a pulp, into an open tank adjacent to the boiler, A. The expansionchamber, C, may be provided with a pipe leading to a steamgauge, to indicate the pressure of steam in the boiler. Claim. Having thus described my invention, what I claim is a boiler for boiling, under pressure, wood and ligneous materials for making paper-pulp, constructed with an expansion-chamber, stirrers, and discharge valve or cock, arranged for the purposes and in the manner substantially as herein stated. In regard to this patent, the main question seemed really to be whether or not it was for a combination. The proofs showed that the defendants had never employed two stirrers, nor even one having arms upon one side alone, capable of Statement of the case.-Keen's patent, A.D. 1863. being turned outwardly when the boiler was filled, so as not to impede the filling or emptying of it. They used for some time a single shaft provided with four blades, shaped like those of a propeller; used, in other words, an ordinary stirrer; but this they abandoned, they having found that from its being under the expansion-chamber and under the aperture for supply, it impeded the filling and emptying of the boiler. This abandonment was about the time when the bill in this case was filed. Messrs. Renwick and other experts of the defendants testified that in their opinion the contrivance of the defendants did not infringe this patent of Keen. Dr. Rand, an expert in chemistry but not in mechanics, who was called for another part of the case, but was examined in this, gave it as his opinion that it did. 2. The SECOND of Keen's patents purported to be for "improvements in boilers for making paper-pulp," and contained the following Specification.* In boilers, where a perforated diaphragm is placed in the interior, and through which diaphragm the material out of which the pulp is to be made is to be charged into the cylinder, it is found that the material falling upon the diaphragm chokes up its openings; and, moreover, gets above or on top of the liquid, which it is the special object of the diaphragm to prevent. My object and purpose is to prevent this difficulty; and I have achieved it in a very simple manner. My invention consists in connecting the man- or feed-hole in the shell of the boiler with the man- or feed-hole through the diaphragm, by a perforated well or cylinder, so that the material can be charged through said well into the boiler without falling upon or clogging the perforated diaphragm. To enable others skilled in the art to make and use my invention, I will proceed to describe the same, by reference to the drawings. A, represents a boiler, which stands vertically in the furnace or brickwork, and which, for strength and convenience, has * The drawing on p. 585 represents the boiler in elevation, with a portion of its upper part represented in section, to show the interior arrangement thereof. |