FARM EXPERIMENTS AT LAKESIDE. 107 



the gelatine is in part removed, and the cell-struct- 

 ure, before tough and refractory, becomes brittle, 

 and is readily broken up by grinding. After steam- 

 ing, they can be ground in an ordinary plaster mill 

 without obstructing the movements of the stones, 

 and without requiring a greater expenditure of 

 power than is needed to grind common gypsum. 

 The only mill ever constructed, so far as I am in- 

 formed, that will grind raw or unsteamed bones fine 

 enough for agricultural uses, is what is known as 

 the atmospheric centrifugal machine, which does its 

 giant work by the single power of attrition. The 

 fragments of bone are allowed to fall into a strong 

 iron drum, which is made to revolve with immense 

 velocity, and bv the action of air, and of the frag- 

 ments upon themselves, they are instantly reduced 

 to an impalpable powder. 



The rich nitrogenous principle of the bones used 

 upon my farm, the gelatine, was secured and com- 

 posted with dry peat and bone dust, and this was 

 found to afford a most efficient top-dressing for grass 

 lands. Thus, in the process of steaming nothing 

 was lost. The cost of preparation was about equal 

 to the original cost of the bones, and hence I have 

 estimated it at twenty-five dollars the ton. The 

 present market price of bone dust is sixty dollars 

 the ton, which affords a wide margin between the 

 expense of mv bone material and that obtained 

 throuo-h commercial channels. 



