224 Composition and Value of Guano. 



Whatever opinion the reader may entertain of the value of 

 potasli as a direct application to the soil — whether he may think 

 it highly important, or may deem it unnecessary or productive of 

 no beneficial results^ still it becomes any individual who shall 

 attempt to fix a money value on a compound manure like guano 

 to be prepared with a price which shall approximate to the com- 

 mercial value of all the important ingredients. It will be at the 

 option of the reader to allow or disallow the value which is thus 

 attached. 



Potash is supplied commercially by four principal salts : — 

 carbonate of potash, known as potashes or pearlashes ; nitrate of 

 potash, or nitj^e ; muriate of potash ; and sulphate of potash.* 



In the first of these (the carbonate), potash is bought at from 

 5d. to 6Jf/. per lb., according to the varying market-price of the 

 salt. 



In nitrate of potash we shall buy potash at 6|^. per lb. 



Sulphate or muriate of potash will, however, furnish us with 

 this alkali at the rate of 2ld. per lb. 



The wide difference in price between the two former and two 

 latter sources is due to the circumstance that the nitrate of potash 

 is more valuable in commerce for its combination with nitric acid 

 than for the potash itself, and the carbonate for its adapta- 

 tion to the purposes of an alkali. In the sulphate and muriate 

 we have the real value of the potash, these being both refuse salts. 



With a knowledge of the approximative value of its three im- 

 portant ingredients, our attention may now be turned to the 

 money value of guano itself; — this being the only object of all 

 the preceding calculations. It has been seen that the average 

 composition of Peruvian guano is the following : — 



Ammonia . . . . . 17*41 per cent. 

 Phosphate of lime . . . 24-12 „ 

 Potash 3-50 „ 



Taking ammonia at its price as supplied by the sulphate — that 

 is to say, at 6d. a lb. ; phosphate of lime as it may be bought in 

 bones or Saldanha Bay guano, at |c?. per lb. ; and lastly, valuing 



* The market value of the diffeient salts of potash is far from constant. For the 

 calculations above, 1 have made use of the following prices, which perhaps will be 

 sufficiently correct : — 



Carbonate of potash, from 28s. (o 42s. a cwt. 



Sulphate, 12s. a cwt. 



Muriate, 135. „ 



Nitrate, containing 90 per cent, of real nitre, 28s. per cwt. 



The per centage of potash in these different salts, when pure and dry, is as follows : — 



Carbonate . .68-2 



Sulphate . . .54-0 



Muriate , . . 63*2 (or /^io/rtssm?;i equal to this quantity of potash). 



Nitrate , . . 4fi'7 



