86 



nesium sulphate and the chlorides of maguesium and so- 

 dium. Its average proportion of potash is about 12 per 

 cent, and it is largely employed in the preparation of com- 

 posts and in compounding mixed fertilizers designed to con- 

 tain a moderate potash percentage. 



The muriate of potash met with in commerce generally 

 has a purity of only 80 to 85 per cent., giving a potash 

 equivalent of about 50 to 53 per cent., while the high grade 

 sulphate contains from 45 to 50 per cent, potash, and the 

 low grade sulphate only about 30 per cent, of this ingredient. 

 These latter goods are used almost exclusively for the 

 preparation of complete fertilizers with a high potash 

 content. 



Cotton seed hull ashes is a southern product which is 

 quite a valuable source of potash, though its use is largely 

 confined to the States bordering on the Atlantic. 



The hulls removed from the cotton seed, preparatory to 

 the extraction of oil, are largely used as fuel under the 

 boilers of the oil mills, and the ashes obtained are found to 

 contain from 15 to 25 per cent, potash, and 7 to 10 per cent, 

 of phosphoric acid. 



In mixing hull ashes with nitrogenous organic materials, 

 great caution is to be observed, since mixtures of this kind, 

 if kept for any length of time, especially if allowed to be- 

 come moist, are likely to ferment, with consequent loss of a 

 considerable proportion of nitrogen. 



Among the chief vegetable sources of potash may be 

 mentioned tobacco stems, which are utilized to a great ex- 

 tent in the tobacco growing States, and many of the com- 

 plete fertilizers manufactured along the Atlantic seaboard 

 contain potash derived from this waste product. 



(4.) MANURES CONTAINING PHOSPHORIC ACID AND NITROGEN. 



Bones, whether in the original crude state or treated with 

 sulphuric acid, contain in addition to their phosphoric 

 acid, from 3 to 5 percent, of nitrogen derived from the gela- 



