On Liquid Manure. 



525 



chano-ed into carbonate of ammonia. This change of urea in 

 a liquid containing a variety of other organic matters proceeds 

 with extreme rapidity. Urea, an organic compound consisting 

 of two equivalents of carbon, two of oxygen, two of nitrogen, 

 and four of hydrogen, has only to take up the elements of four 

 equivalents of water in order to become converted into two equiva- 

 ients of carbonate of ammonia. This change will at once become 

 intelligible by glancing at the following diagrammatic repre- 

 sentation : — 



isr H4 o, c o 



hecome 



1 equival. 

 of urea 



4 equival. 

 of water 



= Carbouatc of 

 ammonia. 



= Carbonate of 

 ammonia. 



As carbonate of ammonia is volatile, and escapes gradually 

 •even from dilute liquids, it is desirable to fix it at once. This can 

 be done most effectually and with little trouble by throwing into 

 the tank from time to time a Winchester quart of brown sulphuric 

 acid. This acid, uniting with the ammonia, drives out the car- 

 bonic acid of the carbonate, which causes a more or less extreme 

 effervescence, and changes the volatile carbonate into non-vola- 

 tile sulphate of ammonia — a salt which is far less caustic than 

 carbonate of ammonia, and more valuable than the latter as a 

 fertilising agent. 



The inorganic portion of the liquid manure from VVestonbirt 

 consists principally of alkaline salts. The proportion of potash 

 in these salts is very considerable. Most of the potash men- 

 tioned in the above analysis occurs in the state of bicarbonate of 

 potash ; there is also a good deal of chloride of potassium and 

 some sulphate of potash. Pliosphoric acid, on the other hand, 

 exists only sparingly in this, and, I may add, in most other kinds 

 of liquid manure ; and as this acid is so essential for the healthy 

 growth of all cultivated crops, we can readily understand that 

 liquid manure, however valuable it may be in other respects, on 

 account of the great deficiency of phosphoric acid and the pre- 

 ponderance of ammonia, when applied by itself to grass-land pro- 

 duces an over-luxuriant and rank herbage, and when applied 

 to a white crop produces corn more remarkable for long, coarse, 

 and abundant straw than for fine and plentiful grain. 



Liquid manure, when produced exclusively from the liquid 

 -excrements of horses, cattle, or pigs, cannot, on account of this 



