Recent Publications on Manures. 73 



The small popular treatise lately published by Mr. Squarey, 

 on Agricultural Chemistry, will be useful to farmers and gar- 

 deners, as a digest of the publications of Liebig, Daubeny, and 

 Johnson on the same subject; and the new matter brought 

 forward on guano and other subjects is very interesting. He 

 dwells much on the value of nitrogen. " Animals," he says, 

 " fed on grass produce fat, as they get a greater proportion of 

 carbon than nitrogen ; those fed on seeds and grains, which con- 

 tain more nitrogen or azote, produce more muscular flesh, as 

 muscle, being highly azotised, requires much nitrogen for its 

 formation." He quotes from Professor Daubeny, to show that 

 wheat grown with human urine had as high as 35 per cent of 

 gluten, while that from cow-dung had only 12 per cent; the 

 carbon predominating in the wheat in proportion to the defi- 

 ciency of gluten. He enters at great length into the subject of 

 urine, showing the vast loss that is incurred annually by the 

 waste of this precious substance, especially human urine. As 

 the nitrogen found in the urine is the surplus of what is 

 needed to be fixed in the system of the animal, with that pro- 

 duced from the waste of the system, carnivorous animals, which 

 feed on more highly azotised substances, must always have more 

 nitrogen in the urine than herbivorous animals. He proposes 

 to fix the volatile carbonate of ammonia in urine and gas tar by 

 sulphuric acid, or vitriol, which may be got, he says, at from Id. 

 to 3d. per lb. ; and every pound of vitriol will form 2 lb. of 

 sulphate of ammonia. He says, the urine should be poured on 

 sawdust, tanner's bark, or dried peat, after lying in the tank or 

 other reservoir till the smell of ammonia denotes that putre- 

 faction has begun ; and the compost should be afterwards mixed 

 with sulphuric acid till effervescence ceases. In this way, he 

 thinks, is the urate of commerce formed ; or, if poured on stable 

 manure and wood ashes, nitrate of potash (saltpetre), he says, 

 would then be formed. 



The great value of nitrogen, as pointed out by Professor 

 Liebig and others, I have before noticed. Professor Dumas 

 says, " chemistry is so far advanced in this respect, that the 

 problem of the production of a purely chemical azotated manure 

 cannot be long in being resolved. As for carbon," he says, " the 

 rain water and air suffice for it." He notices, however, that 

 " recent trials show that the nitric acid of the nitrates also merits 

 particular attention." It has lately been carried so far, that it 

 has been reckoned the only valuable substance in manures, and 

 tables have been furnished by Boussingault and Payen (see 

 Gard. Chron., Oct. 2.), showing the relative proportions the dif- 

 ferent kinds of manure bear to cow-dung in value ; in which the 

 quantity of ammonia (not nitrogen) they contain is taken as the 

 sole basis. There must, however, be some limit to this: nitrogen 



