182 BOARD OF AGRICULTURE. 



have been used in various ways, one portion in the raw or 

 natural condition, another by rotting in contact with moist soil 

 or peat, another for obtaining phosphoric acid, and in other 

 forms for experimental purposes. 



The other agents have been employed alone and»in such com- 

 binations as was demanded to conduct the experiments under- 

 standingly, and in accordance with correct scientific deductions. 

 I regret that time and space will not allow of a detailed account 

 of the results of these experiments, as they are certainly inter- 

 esting and instructive. The statement presented is a general 

 one, given for the purpose of affording a comprehensive idea of 

 the extent and nature of the labors undertaken, and as prei)ara- 

 tory to the presentation of the details of a few experiments of 

 a more special character. During the past three years, atten- 

 tion has been given to the production, saving and application to 

 the soil of animal excrements, and these observations ought not 

 to pass unnoticed. 



The cost of the bones and most of the other agents used upon 

 the farm was less than they could be obtained at the present 

 time, as they were purchased during the years of great depres- 

 sion which existed in the time of the war. Twelve tons of raw, 

 uuground bones were purchased at the start, at a cost of only 

 twelve dollars per ton. They were placed in a large steam- 

 boiler, constructed of iron, and submitted to the action of high- 

 pressure steam for a period of twelve hours. They were then 

 removed, allowed to cool, and immediately reduced to a powder 

 by grinding in a machine resembling a common burr-mill. 

 Bones by steaming are changed in their physical structure, the 

 animal portion or the gelatine, is in part removed, and the cell- 

 structure, before tough and refractory, becomes brittle, and is 

 readily broken up by grinding. After steaming they can be 

 ground in an ordinary plaster mill without obstructing the 

 movements of the stones, and without requiring a greater ex- 

 penditure of power than is needed to grind common gypsum. 

 The only mill ever constructed, so far as I am informed, 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 simple 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 by 



