Explosives . dded inthe form of whiting. To remove the great bulk of the water the pulp may now be passed intoa centrifugal machine, lined with fine canvas. The dam]) ma>s thus obtainedstill contains 40 or 50 per cent, of water. It may be Bent away from the gun- THE STABILIZATION OF NITRO-CELLULOSE 187 cotton factory in this form, or it may be moulded first into blocks. This isdone by loading it into a hydraulic press, where it is subjected to a pressureof 30 or 40 lb. per square inch. Presses are also made which dispense withthe preliminary wringing in the centrifugal machine. These have h
Explosives . dded inthe form of whiting. To remove the great bulk of the water the pulp may now be passed intoa centrifugal machine, lined with fine canvas. The dam]) ma>s thus obtainedstill contains 40 or 50 per cent, of water. It may be Bent away from the gun- THE STABILIZATION OF NITRO-CELLULOSE 187 cotton factory in this form, or it may be moulded first into blocks. This isdone by loading it into a hydraulic press, where it is subjected to a pressureof 30 or 40 lb. per square inch. Presses are also made which dispense withthe preliminary wringing in the centrifugal machine. These have hollowplungers covered with fine wire gauze, and the bulk of the water is drawnoff through these by the application of a vacuum. The hydraulic pressureis then applied whereby the gun-cotton is moulded into a block or cylinder,which can be handled conveniently. An important point concerning the beating engine is to secure a very The beatergood circulation of the water. In the machines used in the paper industry. Fig. 37. Beater for Pulping Gun-cotton. the rotation of the drum causes the water to move round so fast that thefibrous cellulose material cannot settle, but is carried round and round, sothat it comes repeatedly under the knives, until it has been reduced totherequired degree of fineness, and the machine requires very little attentionBut if the same machine be used to pulp nitro-cotton, it is found that thesolid material tends to settle down at the bottom, and it is necessary for aman to attend the machine and help the material round with a wooden is not due entirely to the increase of the specific gravity, for that ofnitro-cotton is only 1-67. whilst that of cotton is about Mil. but in the nitra-tion the weight of each fibre has increased about 70 per cent. The lengthhas not become Greater, probably it has diminished somewhat, consequentlyeach fibre has become much stouter, as may be seen clearly on comparingmicro-photos 1 ami 7, Fig. 30. There is therefore
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