244 SOILS AND MANURES 



i.e., the bone superphosphates as dissolved bones have 

 been occasionally called. The name " bone superphos- 

 phate " has also been applied to samples of ordinary 

 (mineral) superphosphate with which a quantity of raw 

 bones has been mixed. Such a mixture has much to 

 recommend it for certain purposes, but it is generally 

 better to apply the two substances to the soil separately 

 the latter preferably at the back end of the year, and 

 the former in the spring. In any case such mixtures 

 should not be confused with dissolved or vitriolated bones. 

 They have often been sold under that name, but it is 

 now illegal to do so, and they are generally described as 

 dissolved bone manures or bone Compounds. 



It is sometimes argued that they are just as good as 

 pure dissolved bones, but if that be true, the purchaser 

 should remember that the two substances can generally 

 be obtained separately at a cheaper rate. 



In some districts there is a popular idea that the 

 terms dissolved bones and vitriolated bones have refer- 

 ence to some difference in the treatment or composition of 

 the manure, but they are really only alternative names 

 for the same substance. 



The acid used in the treatment of bones is generally 

 more concentrated than that employed in the manufacture 

 of mineral superphosphates. As a rule only about half 

 the total phosphate is rendered soluble, but the re- 

 mainder is partially acted upon, and is largely converted 

 into the dicalcic form. A larger quantity of acid cannot 

 well be used, as the product has a tendency to become 

 wet and sticky, and in that condition cannot be evenly 

 distributed over the land. 



The composition of dissolved bones depends .partly 

 upon that of the raw bones from which they are pre- 

 pared, and partly upon the quantity of acid with which 

 they have been treated. In general, they contain from 



