212 ARTIFICIAL MANURE. 



But unless the impurities of the commercial alkalies are 

 known it may not be prudent to substitute pot or pearlashes, 

 and soda or white ash, either for one another, or for ammonia 

 in the usual state, in the above proportions. All alkalies 

 in the market are now much purer than formerly. 



1st quality pot and pearlashes contain, on the average, 83 

 per cent, of carbonate, and no perfectly caustic alkali. 2d 

 quality pots and pearls average 71 per cent, carbonate. 

 English soda ash contains in its perfectly dry state 81.5 per 

 cent, of pure carbonate, and about 2.75 of caustic soda = 

 4.68 carbonate, or the total carbonate is equal to 86 per 

 cent., which, in the commercial state of fair soda ash is equal 

 to 80 per cent. 



The proportions then become, 



t 



59 pure carb. ammonia = 61 commercial, 



54 " soda = 67 soda ash of 80 per cent. 



70 " potash = 84, 1st qual. pots or pearls, 



70 " " =98, 2d " " " 



Fortunately for agriculture, rigid accuracy is not her© 

 required. The farmer need not fear to use the commercial 

 alkalies because he knows not their chemical composition. 



265. For all agricultural purposes, it may be considered, 

 that salts of hartshorn, or carbonate of ammonia, and white 

 or soda ash, are equal, pound for pound, and that pots and 

 pearls may be taken at one-half more. 



266. If all the nitrogen in dung becomes ammonia, then, 

 as has been shown (187), each 100 lbs. affords 2 lbs. 2 oz. 

 Discarding fractions, let it be called 2 lbs. Hence, if to 

 100 lbs. fresh dug peat, there are added 2 lbs. soda ash, or 

 3 lbs. of pot or pearl ashes, all the good effects of real cow- 

 dung will be produced. Peat or muck thus requires 2 per 

 cent, of soda ash, or 3 per cent, of potash. 



