98 PHOSPHORUS. 



only for a time, but it serves to convince us that 

 the stimulus is to the plant and not to the soil. 



ON PHOSPHORUS. 



This elementary matter is never found in its 

 pure state. Combined with oxygen gas, it 

 forms phosphoric acid, and this again united 

 with such bases as lime, soda, magnesia, &c., 

 forms the salts termed phosphates, which are 

 met with in animal, as well as in vegetable 

 products. 



Phosphate of lime is, as will hereafter be no- 

 ticed , the principal i ngredient of bones, of which 

 it forms the hard part. A native phosphate of 

 lime occurs abundantly in Spain, under the 

 name of Apatite, and other native combinations 

 of this acid occasionally are met with. 



Phosphorus is an ingredient in urine, and 

 affords another argument in favour of the use 

 of this matter (hereafter to be noticed) as a ma- 

 nure ; as the presence of the phosphates is es- 

 sential to the growth of vegetables, especially 

 of wheat, barley, oats, and rye, in the grain of 

 which it always occurs, and without which no 

 such crop could be perfected, and from this 

 source also the human frame derives its supply 

 of this necessary matter. 



The native phosphates exist in a greater or 

 less degree in all soils, and vegetables there 

 find the supply they require for their growth 

 and development. But as this essential is as 

 easily exhausted by a crop, as the other salts 



