CHAPTEE XIII. 

 MANUFACTURE OF MANUEE FROM ANIMAL WASTE. 



Prelmiinary Remarks. — The utilization of waste of animal origin is 

 of the same economical importance as of human excreta. like the 

 latter, the products have come from the soil and been paid for in 

 the manure. Unfortunately, these wastes are not collected with 

 sufficient care, in spite of the great facility with which they can be 

 utilized. Vast quantities of blood are annually lost in the slaughter- 

 houses of both large and small towns, where the air is infected by 

 the products of its decomposition. Numerous animal carcases are 

 buried every year, not only through following an old custom, but 

 moreover in order to obey certain prescriptions of the sanitary 

 police. Their conversion into chemical manure is their best dis- 

 infection. In this conversion all animal matters are boiled, which 

 not only destroys living organisms, but also the germs of putre- 

 faction and the germs of contagious diseases. Moreover, as animal 

 matters are not long in beginning to putrefy if left to themselves 

 after boihng, manure manufacturers have the greatest interest in 

 avoiding this decomposition, because it always entails a certain loss 

 ■of nitrogen, its most valuable constituent. This is effected by dry- 

 ing, for dried animal matter can be stored for years without decom- 

 posing. By examining the methods used for the manufacture of 

 manures, it will be seen that they not only afford means of making 

 an excellent profit from animal waste, but also of destroying all the 

 •contagious germs which they may contain, and that therefore the 

 police regulations which require all animals that have died from 

 infectious disease to be buried, are thus quite contrary to economy 

 :as well as to well-conceived hygienic measures. The animal matters 

 rich in nitrogen most often utilized in manure manufacture are — 

 blood, meat (flesh), horn, and leather waste. 



Blood.— Fresh blood forms a red thick liquid of density I'Odo 

 to 1-575 (6 to 7° B.) (9 to 15° Tw.). In contact with free air it 

 ■soon separates into two parts, one solid, fibrous, forms the clot, 

 whilst the other, liquid, constitutes the serum. The clot consists 

 mostly of fibrin, whilst the serum especially contains dissolved 

 •albumen (7 to 8 per cent). Blood contains per 1000 parts, 796 of 

 water and 201 parts of solid. The solids consist of : — 



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