AUXILIARY AKD EXCEPTI0:N"AL MANURES. 87 



dust, and thoroughly incorporated. In the pasty condi- 

 tion to which the sulphuric acid reduces the bones, it is 

 quite impossible to apply it either by hand or drill ; wood- 

 ashes, peat-ashes, or even dry soil may be used to prepare 

 them for sowing ; but quick-lime, or powdered chalk, 

 must not be mixed with the dissolved bones for the pur- 

 pose of drying, as the lime would restore them to their 

 comparatively insoluble condition. 



By dissolving bones their effect on the turnip crop is 

 greatly increased. Superphosphate is applied at the rate of 

 four to five hundred pounds per acre, when used by itself. 



Superphosphate is also prepared by treating bone-ash 

 and coprolite or mineral phosphate with sulphuric acid. 



The difference between the effects produced by animal 

 phosphate and mineral phosphate is virtually nothing, 

 but the difference in price is yery considerable. 



The farmer may manufacture his own superphosphate. 

 An iron tank or a strong wooden vat is used in prej)aring 

 it, TJie bone-ash or coprolite powder to be dissolved is 

 put into the tank, and over it is poured one-fourth its 

 weight of water. AfterAvards stir and mix well ; then add 

 sulphuric acid ecjual to about half the weight of bone-ash, 

 or more of mineral phosphate, and again stir and mix 

 thoroughly. The finer the division of the ground phos- 

 phate the more rapid and effectual is the process. If am- 

 monia is wanted in the subsequent manure, it can be sup- 

 plied by an addition of sulphate of ammonia. After re- 

 moving the superphosphate from the tank, if it is placed 

 in a heap under cover and allowed to remain for a suffi- 

 cient time, the moisture will evaporate by the heat of the 

 mass. It will lose in weight according to the time it re- 

 mains in the heap, but there will be an increase in the 

 percentage of soluble phosphate. The same substances 

 may be used for drying the superphosphate, however, as 

 have been recommended for drying dissolved bones. 



