186 MANURE. 



teine being calculated on its nitrogen. Tlie physiological 

 view is this : 



If ammonia and water, known compounds of nitrogen, 

 hydrogen, and oxygen, are added in certain proportions to 

 proteine, all the gelatinous tissues, hair, horn, &c., will be 

 formed. 



Let Pr. represent proteine, then 



By this view, horny matter exceeds by 16 per cent, and 

 the gelatinous tissues by 25 per cent., the value of the pro- 

 teine of flesh, blood, &c. 



220. For the purposes in view, all animal and vegetable 

 products may be divided into two classes : first, that which 

 does, and second, that which does not, contain nitrogen. 

 The action of these is very distinct, on the elements of soil, 

 and as manures. The first class putrefies, the second does 

 not. The first class forms alkali, the second forms acids. 

 The action of the first depends on nitrogen, that of the second 

 on carbon. 



221. The first class contains flesh in all its varieties ; blood, 

 skin, sinew, gristle, cartilage, tendons, hair, feathers, wool, 

 hoofs, horns, nails, scales, and one-third, nearly, of bones 

 and teeth. The second class contains fats and oils in all 

 their variety. 



222. It is easily understood, then, how woollen rags and 

 flocks become powerful manure. They aflford ammonia, and 

 100 lbs. containing 17 of nitrogen, should be 34 times 



