MANUEE FROM ANIMAL WASTE. 259 



during the process there can be no alteration of the material, either 

 by fermentation or by superheating, the portion evaporated consists 

 simply of pure water without trace of smell. 



Di-yiag lasts six to seven hours and induces the agglutination of 

 certain portions into hard masses so as to obtain an impalpable 

 powder ; the dried mass is pulverized in a Carr's crusher completely 

 enclosed in a wooden case and in communication with an aspirator 

 for dust recovery. 



All these operations follow each other. The fresh blood is con- 

 verted in less than ten hours into a powder which is bagged up 

 ready for immediate delivery. As will be seen further on, 1000 

 litres (220 gallons, say 1 ton) of blood from the Villette slaughter- 

 houses yields with these machines 210 kg., say in round figures 4 

 cwt. of dried blood. According to multiple experiments made at 

 the Aubervilliers factory, the coal used for all these conversions is 

 estimated at 0-833 lb. per lb. of dried blood. They calculate that in 

 actual practice 5 tons of coal suffice to convert 284- tons of liquid blood. 

 The motor power is at a maximum for three driers of 15 cul3ic metres 

 each. The improvement in the yield due to these machines is con- 

 siderable, as results from the following experiment. After previously 

 mixing, 16 metric tons of blood, coagulated by ferric sulphate, and 

 containing 62 to 65 per cent of water, was divided into two lots ; 

 the first lot of 8 tons, dried in a hot-air oven, yielded 2*555 metric 

 tons, say a yield of 31*5 per cent. The lot of 8 tons, treated in a 

 Donard machine, gave 3^ tons of dried blood, say a yield of 15 per 

 cent. The percentage of water in the dried blood from the two 

 treatments was perceptibly equal, 15 to 16 per cent. The difference 

 of yield, 13*5 per cent, shows the loss the dried blood undergoes by 

 overheating in the hot-air oven above-mentioned. 



Meat Meal. — As far back as 1863 manure was made at Auber- 

 villiers (Seine) from dead animals or animals slaughtered in the 

 department of the Seine and its neighbouring departments. The 

 fat was first extracted for the knackers and the rest was converted 

 into manure. The flesh was cooked by steam, then pressed to ex- 

 tract the fat, dried, and ground. The bones were also boiled, then 

 dried and crushed to a fine powder. Finally, with the entrails, the 

 boilings and the residues of the organic matter, composts were made 

 of low nitrogen content. Thev were mixed with the residues from 

 the manufacture of fat (? greaves), ground mineral phosphates, bone 

 residues, fur, etc., were added, and the whole piled in a heap and 

 drenched with blood and boilings. These substances, difficult to 

 assimilate, especially ground mineral phosphates after an active and 

 prolonged fermentation, undergo slow conversion which renders them 

 assimilable. The composts mixed in different proportions with rich 

 substances, dried meat meal, dried blood or crashed bones, enable 

 manures of all strengths to be prepared containing 1*5 to 2*5 per 



