NITROGEN IN EXCREMENTS. 183 



In Paris, for example, the excrements are preserved in the 

 houses in open casks, from which they are collected and placed 

 in deep pits at Montfauqon, but they are not sold until they have 

 attained a certain degree of dryness, by evaporation in the air. 

 But whilst lying in the receptacles appropriated for them in the 

 houses, all their urea is converted for the most part into carbonate 

 of ammonia : the vegetable matter contained in them putrefies, 

 all the sulphates are decomposed, and the sulphur forms sul- 

 phuretted hydrogen (volatile hydrosulphate of ammonia). The 

 mass, when dried by exposure to the air, has lost the greatest part 

 of its nitrogen along with its water, and the residue, besides phos- 

 phate of ammonia, consists for the most part of phosphate of lime 

 and magnesia, together with fatty matters. This manure is sold 

 in France under the name of Poitdretle, and is very highly esti- 

 mated, on account of its powerful action. This action cannot 

 depend on the ammo-Jr. originally contained in it, because the 

 greatest part has escaped during the desiccation. According to 

 the analyses of Jaquemars, the Parisian poudrotte does not con- 

 tain more than 1*8 per cent, of ammonia. 



In other manufactories of manure, the night-soil, whilst still 

 soft, is mixed with the ashes of wood, or with earth, &c, con- 

 taining a large quantity of caustic lime, and this causes a com- 

 plete expulsion of all the ammonia of the excrements, depriving 

 them ill consequence of all smell. The efficacy of thiVmanure 

 cannot, therefore, depend upon its nitrogen. 



It is evident that, if we place the solid or liquid excrements of 

 man, or the liquid excrements of animals on our land, in equal 

 proportion to the quantity of nitrogen removed from it in the 

 form of plants, the sum of this element in the soil must increase 

 every year; for to the quantity which we thus supply, another 

 portion is added from the atmosphere. There is no proper loss 

 of nitrogen to plants, for even the small quantity of this element 

 which man carries with him to the grave is not finally lost to 

 vegetation, for it escapes into the earth, arid into the atmosphere, 

 as ammonia, during the decay and putrefaction of the body. 



A high degree of culture requires an increased supply of ma- 

 nure. With the abundance of the manure the produce in corn and 

 cattle will augment, but must diminish with its deficiency. 



