AGRICULTURE WITH CHEMISTRY. 75 



PHOSPHAT OF LIME 



Is contained in animal matters, such as bones, 

 urine, shells, Sec. Sec. in some sorts of limestone, and 

 in vegetable substances, particularly in the gluten, or 

 vegeto-animal matter of wheat or other grain. It is a 

 saline compound very insoluble. There is reason to be- 

 lieve, a very considerable proportion of this nearly inso- 

 luble salt is contained in most fertile soils, especially 

 those that have been long under cultivation. It is not 

 to be decomposed by pure alkalis ; but this may be ef-' 

 fectecl by mild vegetable and mineral alkalis, on the 

 principle of the double electrive attractions ; in which 

 case, carbonat of lime (or chalk) will be precipitated, 

 and the phosphoric acid will join with the alkali, and 

 form phosphat of potash, or phosphat of soda, according 

 to the alkali applied. These alkaline phosphats will be 

 found to promote vegetation in a very great degree : 

 the substances of which they are composed, viz. alka- 

 line salts and phosphoric acid, are found in the ashes 

 



of most vegetables. 



K 2 PIIOS- 



