NIGHT-SOIL. 193' 



|by the living organism ; it is soluble in water, and 

 can be thus absorbed by the roots of plants, and its 

 nitrogen assimilated in the form of ammonia, and of 

 the oxalate, hydrocyanate, or carbonate of ammonia. 

 It would be extremely interesting to study the 

 transformations which uric acid suffers in a living 

 plant. For the purpose of experiment, the plant 

 should be made to grow in charcoal powder pre- 

 viously heated to redness, and then mixed with pure 

 uric acid. The examination of the juice of the plant, 

 or of the component parts of the seed or fruit, would 

 be a means of easily detecting the differences. 



NIGHT-SOIL. 



In respect to the quantity of nitrogen contained 

 in excrements, 100 parts of the urine of a healthy 

 man are equal to 1300 parts of the fresh dung of a 

 horse, according to the analyses of Macaire and Mar- 

 cet, and to 600 parts of those of a cow. Hence it 

 is evident that it would be of much importance to 

 agriculture if none of the human urine were lost. 

 The powerful effects of urine as a manure are well 

 known in Flanders,* but they are considered in- 

 valuable by the Chinese, who are the oldest agricul- 

 tural people we know. Indeed, so much value is 

 attached to the influence of human excrements by 

 these people, that ]aws of the state forbid that any 

 of them should be thrown away, and reservoirs are 

 placed in every house, in which they are collected 

 with the greatest care. No other kind of manure 

 is used for their corn-fields, f 



* See the article "On the Agriculture of the Netherlands," Journ. 

 Royal Agri. Soc.^ Vol. II. part 1, page 43, for much interesting informa- 

 tion on this subject. 



t Davis, in his History of China^ states that every substance con- 

 vertible into manure is diligently husbanded. '' The cakes that remain 

 after the expression of their vegetable oils, horns and hoofs reduced to 

 powder, together with soot and ashes, and the contents of common: 



17 



