Phosphates 



this work. We do not consider that it is used 

 sufficiently in England, although the economy 

 of employing it has been shown by numerous 

 demonstrations. 



There is any amount of waste land only requiring 

 to be slagged to be brought under cultivation. Its 

 use is not justified simply because of its reputation, 

 but because that reputation is genuine, and because, 

 moreover, the price is reasonable, being generally 

 a quarter less based on the unit than that of the 

 unit in superphosphate, and not so dear as that of 

 bone meals. 



It usually contains from 9 to 18 per cent, phos- 

 phoric acid, corresponding to 20 to 40 per cent, 

 tribasic phosphate. Sometimes, however, the con- 

 tent of phosphoric acid is as much as 22 per cent, 

 or 48 per cent, tribasic and more, according to the 

 kind of mineral from which the slag is derived. 



Here is its average composition : — 



Basic slag must always be bought on analysis 

 and with a guarantee of the quantity of P2O5 

 soluble in citric acid. The gross content of phos- 

 phoric acid can never be accepted as the price basis. 

 If it were it would be an incentive to adulteration 

 with insoluble phosphates. The purchaser should 

 see, therefore, that the phosphates are all original, 



64 



