William Strong

“ My invention relates to the construction of a boiler for boiling wood and ligneous materials for making paper-pulp, in which proper provision is made for keeping the stock covered by the alkali or liquid used, and giving it motion, to insure the mass being properly boiled throughout, and a discharge valve or cock, by means of which the stock when sufficiently boiled is blown out in a pulpy state.
To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation. ”

“ It is insisted, however, that the paper-pulp which had been produced before the invention of Watt & Burgess was not pure cellulose, that it was only approximately pure, and from this it is argued that the pure article obtained from wood by their process is a different and new product, or manufacture. Whether a slight difference in the degree of purity of an article produced by several processes justifies denominating the products different manufactures, so that different patents may be obtained for each, may well be doubted, and it is not necessary to decide. ”

“ It is freely admitted that the patent of an originator of a complete and successful invention cannot be avoided by proof of any number of incomplete and imperfect experiments made by others at an earlier date. ”

“ It is true the patent cannot be extended beyond the claim. That bounds the patentee's right. But the claim in this case covers the whole process invented, and the complainants seek no enlargement of the process. Certainly the claim of the process ought not to be regarded as excluding all other substances than the one mentioned. As already noticed, the specification avows the object of the invention to be a process for treating straw and other vegetable fibrous materials requiring like treatment preparatory to the use of such fibres in the manufacture of paper. ”

“ The straw or fibrous materials and a weak solution of caustice alkali are then to be placed in a suitable close boiler, heated by steam, as hereafter explained, and the heat is to be raised to such a degree as to attain and maintain for a time, a pressure internally of the boiler equal to or exceeding seventy pounds on the square inch, that is, about 310° of Fahrenheit, by which means a considerable saving of alkali, as well as time and fuel, results, as compared with the means of using a hot solution of caustic alkali, as now practiced in preparing straw and other fibres for papermakers. ”

“ The alkaline solutions having been removed by precolation and washing, or by pressure and washing, the wet mass of woody or vegetable pulp is now to be exposed to the action of chlorine, or the compounds of chlorine with oxygen, for the purpose of bleaching it and preparing it for the manufacture of white paper. Brown, colored, or unbleached paper, of a good quality, can be produced from the pulp as soon as the alkaline solutions are removed; but for the production of good white paper, it is necessary to subject the pulp to the bleaching process. ”

“ In the interior of the boiler, near its upper end, there is placed a perforated diaphragm, B, through the centre of which there is an opening, c, c, and at the top or crown of the boiler there is also a man- or feed-hole, or opening, a, a, and these two openings, a, c, are connected by a perforated well or cylinder, G, to act as a guide for the material being charged into the boiler, and to prevent it from falling upon the perforated diaphragm, and thus not only choking its openings, but getting on top of the liquid, which it is important to avoid as damaging to the pulp. ”

“ The language of the patent is not 'straw and other like vegetable materials.' The specification speaks of 'straw or such other fibrous matters,' of 'straw or fibrous matters,' of 'straw or fibrous substance,' 'straw or other fibrous material,' and it uses other similar forms of expression, but all of them clearly referring to fibrous materials requiring treatment like that required by straw for the production of paper-pulp. ”

“ We think it evident that the novelty and usefulness of the Keen combination, so far as it relates to the stirrers, is in their construction and location, so as to avoid the obstruction to filling and discharging the boiler, which was caused by the use of such an agitator as the defendants employed. We cannot, therefore, hold that this patent has been infringed by the defendants. They have not used all the constituents of the combination, nor employe any equivalent device which produces, or is calculated to produce, the same effects. ”

“ The boiler is to be filled with straw and alkaline solution and then closed fluid and steam-tight. The boiler is made to revolve slowly, say about one or two revolutions per minute, and the steam is to be admitted. I find it desirable to keep up the heat and pressure during about three hours after the pressure above mentioned has been obtained, when the process of boiling is complete. A steam-gauge proper y fixed upon the boiler will enable one to ascertain when the pressure has attained the required degree. ”

“ As the defendants have not used a perforated well connecting a feed-hole in the shell with a man-hole in the diaphragm of the boiler, they are certainly guilty of no infringement of the first claim in this patent. They feed their boiler by means of a feed-hole below the diaphragm, not through it. ”

“ The vats which receive the wood shavings or cuttings, or other vegetable substances, being formed into pulp, should be constructed with suitable means of drainage. The alkaline solutions must then be removed from the pulp, either by percolation and subsequent washing in the vats, or by pressure in any convenient apparatus and subsequent washing. The mode of percolation has generally been found sufficient. ”

“ And it is equally clear, in cases of chemical inventions, that when, as in the present case, the manufacture claimed as novel is not a new composition of matter, but an extract obtained by the decomposition or disintegration of material substances, it cannot be of importance from what it has been extracted. ”

“ That the Mellier patent was valid, and that the defendants were infringers of it.
Thereupon the complainants appealed from that part of the decree which related to the Watt & Burgess and the Keen patents, and the defendants from that part which sustained the bill as to the Mellier patent.
To enable the reader to understand perfectly the case, the patents under consideration are all set out. This, with a few remarks and some testimony, &c. interposed, it is hoped will enable the reader, who has any general knowledge of the art of papermaking, sufficiently to understand the case. ”

“ The stirrers are two in number, the shafts of which are placed vertically toward the sides of the boilers, and provided with arms on one side only, in order that they may be turned toward the periphery of the boiler when it is to be charged, so as not to be in the way of the material thrown in. That the stirrers constructed and arranged substantially as described were a material part of the combination is certain, and we think it has not been proved that they were used by the defendants. ”