The Purchase of Artificial Manures. 449 



149-2 lbs. of the muriate or chloride. In the former case 

 therefore, to convert potash into terms of sulphate of potash 

 we multiply by 1*85, whereas in the latter case we multiply 

 by 1 '5 8. If, therefore, an analysis of, say, kainit is stated as 

 1 2 -5 per cent, potash, that is equivalent to saying that it 

 Tiolc's over 23 per cent, ot sulphate of potash ; while muriate 

 •of potash guaranteed to contain 56*8 per cent, of potash is 

 •of about 90 per cent, purity. 



Just as a buyer may sometimes be led into purchasing a 

 manure through its nitrogen being expressed as sulphate of 

 ammonia, so may the contents of potash be made to look 

 more attractive by being stated as sulphate of potash. In an 

 invoice, however, the potash must be stated as such. 



The rules for approximately converting the various terms 

 into their equivalents maybe thus summarised : — 



To convert Nitrogen into terms of Ammonia multiply by 1*2 



.,, „ Nitrogen ,, ,, Sulph. of Ammonia 47 



.,, ,, Phosphor. Acid ,, Phosphates ,, ,,2*2 



Potash ,, ,, Sulphate of Potash ,, 1-85 



,, Potash Muriate of Potash ,, 1*58 



Nitrogen and phosphates, and, to a less extent, potash, 

 vary in effectiveness, and therefore in value, according to 

 their source or origin. Nitrogen is never so effective as when 

 in the form of nitrate of soda. It is not quite so active, and 

 for some purposes not so valuable, when in the form of 

 sulphate of ammonia, though under certain circumstances 

 this somewhat slower action may be regarded as an advan- 

 tage. Nitrogen in what is called the organic form is in its 

 least active condition, though here again the rapidity and 

 effectiveness of action vary greatly. Nitrog'en is in the 

 organic form in blood meal, fish meal, bones, shoddy, etc., 

 and yet as a source of plant food blood meal is more active 

 than these other substances. It is claimed as an advantage 

 for slow-acting manures that they last longer, which is true ; 

 but one applies manures not to last, but to act. It is only 

 where it is convenient to apply manure at somewhat long 

 intervals, as in the treatment of orchards, that the more 

 inert manures are worthy of much consideration. 



As regards phosphatic manures, it may be said that while 

 soluble phosphates are all alike active, there is considerable 



G G 



