178 CHEMICAL MANURES. 



arrange two pair of rolls on the same framework. The second 

 crusher has shorter teeth, and its rolls nearer. The largest pieces 

 issuing from the second roll must not be larger than a small hen's 

 egg, in order subsequently to get a good fat extraction. 



(2) Very Quick-speed Machine. — To this class belong Weid- 

 knecht's (F.) and Carr's. Weidknecht's excellent crusher consists 

 of a very strong framework properly so-called of cast-iron in two 

 pieces, the lower part or pedestal, and the upper part or hood ; these 

 pieces are bolted at their point of contact. The hood is adjusted to 

 the framework, on the one hand, by a joint forming a hinge, and on 

 the other hand bv a screw and bolt joint. Bv this arrangement 

 a single workman is able to inspect the machine, or change the 

 grating in a few minutes. All he has to do is, by a turn of the 

 spanner, to reverse the screw of the bolt joint, and to lift the hood 

 which hinges on its axis. The bearings are of great scope and 

 constant lubrication. Moreover, to diminish the friction surface 

 of the shaft, the plummer blocks are suppressed, and to keep up 

 the lateral play they are replaced by abutment screws which are 

 fitted to each end of the shaft and in contact with the tempered 

 sheaths adjusted consequently in the end of the shaft. 



The shaft thus maintained is filled in its middle with a jacket 

 or boss, on which fixed levers are arranged, at the end of which 

 levers hinged hammers are fixed which work like flails, the hinge 

 enabling the hammer to fold itself back when at work if overfed or 

 if a foreign body be fed into the machine. The mobility is also in- 

 tended to keep the machine from stopping if the belt comes off, 

 if it be not fed automatically. In fact, the hammers, by fold- 

 ing backwards, let the fine 'material pass through the grating 

 arranged in the lower part of the framework ; the apparatus being 

 thus freed, the shaft regains its normal speed without having to 

 stop. The hammers thus form a fly-wheel, storing up active energy. 

 The machine is fitted on its interior lateral faces by toothed steel 

 plates of great hardness ; they are kept in position by bolts and can 

 thus be easily replaced. The hood or upper part is fitted up in the 

 same way on its lateral faces ; moreover, it has on the roof linings, 

 likewise fitted with projections, and fixed by bolts on the shaft 

 is the driving pulley. The machine is in fact very strong, and the 

 pieces easy to replace. There is no heating in spite of the speed, 

 for the ventilation due to the motion is very energetic. The fine- 

 ness of the product depends solely on the dimensions of the grating, 

 which in the case of bones consists of bars wide apart, through 

 which the hammers drive the crushed bones. A crusher with bars 

 less far apart acts as a final crusher, and, as before, a chain cup 

 elevator serves to feed the second with the crushed bones from the 

 first. 1 



1 But each machine built on the disintegrator principle is sold to make fine 

 hone meal. Although the translator has not had much experience of bone crush- 



