96 



CHEMICAL MANUEES. 



and issue from the central aperture. The larger granules contained 

 in the material which have traversed the current of air, without 

 being carried away in its train, fall into the interior cone and issue 

 by the lateral pipe, to repass into the mill if need be. The air 

 returns naturally to the space below the distributor, so that the 

 separator works constantly with the same amount of air, and so as 

 to disengage no dust. The rods, with pins, to be seen on the cover 

 of the separator, serve to raise or lower the annular obturator 

 which regulates the degree of fineness of the substance. The force 

 of the current of air diminishes in proportion as the obturator is 

 raised. By these simple means, any degree of fineness can be 

 secured. Once regulated, it works without interruption and super- 

 vision, and always gives a very uniform product. The ground 

 phosphate can be bagged up directly or conveyed to silos, etc., 

 whilst the granules return to the mill to be further ground. 



Jaw-hreaker Mills, Cracking Mills. — The jaw-breaker mill 

 shown in Figs. 12 and 13 consists essentially of two jaws, a and A', 



Fig. 13. — Jaw-breaker Mill (view from 

 above). 



Fig. 12. — Jaw-breaker Crusher. 



of hardened cast-iron, dented or smooth. One of these jaws A" is 

 fixed on the anterior side of the framework, the other A' is mobile 

 and fixed on a jaw-holder which is animated by a to and fro motion 

 round its axis /. This motion is transmitted by the excentric 

 driving shaft c, through the intermediary of the excentric crank 

 B' and of a folding lever, formed by two hinge plates, BB, applied 

 one on the framework in d and the other on e on the lower part 

 of the movable jaw- holder. To avoid shocks the latter is joined 

 in an elastic manner with the crank B, by means of the spring g. 

 For each revolution of the shaft c the space A comprised between 

 the fixed jaw-blade and the movable jaw is contracted, and its 



