112 PKACTICAL FARM CHEMISTRY. 



phosphate," charging us $22.50 per ton for it. It 

 contains twenty-one to twenty-two per cent of 

 phosphoric acid, claimed to be for the most part 

 immediately available. If this be true, we get our 

 phosphoric acid (at five and a quarter cents per 

 pound) in this article reasonably cheap. It may be 

 worth the trial. The manufacturers also intend to 

 establish large factories in other parts of the country, 

 notably in the north-west, and altogether it seems 

 that we have here a source of phosphoric acid which 

 will become important, especially for many sections, 

 which, remote from the sea-shores, have heretofore 

 been practically excluded from the benefits of phos- 

 phatic manures on account of the heavy tariff levied 

 upon commerce by transportation companies. 



Tankage consists chiefly of offal from slaughter- 

 houses, and is a mixture of partly cooked particles 

 of meat and flakes of bone deposited in 



FiahBcfa^p tanks, in which the refuse from the 



butcher is treated to separate the grease. 



It contains fair percentages of both nitrogen and 



phosphoric acid, the proportion of each generally 



varying inversely with the quantity of the other. 



Fish scrap is obtained by drying and pulverizing 

 the residue left from the extraction of oil from fish, 

 and contains, in addition to nitrogen, a fair propor- 

 tion of phosphoric acid. 



