MANUEE FROM ANIMAL \YASTE. 261 



cent of nitrogen, and up to 25 per cant of phosphate. The mineral 

 phosphates were coproUtes. From time to lime the compost heap 

 was watered with sulphuric acid to avoid loss of ammonia and to 

 reader the phosphates soluble. Tne manure most rich in nitrogen 

 so manufactured contained 12 per cent and a little phosphate. By 

 mixing it with bone dust and alkaline salts, Dulac prepared a 

 manure containing 8 per cent of nitrogen, 12 per cent of phosphates, 

 15 per cent of potash salts, sod i, magnesia, etc. This manure was 

 sold at 24 francs the 100 kg. (^ay JtlO a tonj. The x\ubervilliers 

 factory continues to use meat waste for the manufacture of manures, 

 but it has considerably improved its processes, as will be seen. The 

 blood in powder tests 13 per cent of water and 13'2 of nitrogen; it 

 treats per month on an average 3500 casks of 185 litres (lO*? 

 gallonsj, yielding 155 metric tons of dried blood. 



Drying Blood by Lime. — Recently a simple process has been 

 used to dry blood and to reduce it to a fine powder. This process 

 consists in adding 1^ to 3 per cent of quicklime, which converts it 

 into a solid cake which may be dried in the air without putrefying, 

 and finally gives a fine and inodorous powder. This process has 

 the advantage of being capable of being applied everyw^here without 

 any plant ; moreover, it preserves 0*4 of nitrogen, which otherwise 

 would be lost with the coagulation water. It mav likewise be 

 applied in the country by farmers, who thus possess the means of 

 manufacturing economically an excellent nitrogenous manure. 



Boiling Meat. — Butchers' waste of all sorts, skinned animals 

 cut into pieces, are first boiled in lead-lined vats. The lid of the 

 vat has in its fixed half a square opening to which a wooden sheath 

 fits, the other half, movable around two hinges, is used to feed in the 

 materials to be treated. Each vat is charged with — 



Meat, et? SOO kg. 



Water loO „ 



Sulphuric acid . . . . . . . . 50 ,, 



The vat being charged, the lid closed, and steam turned on, the 

 boiling lasts about twelve hours. The vertical wooden sheaths on 

 the top of the vats form real draught chimneys branching into two 

 large horizontal collectors which end in a maso iry turret ; there 

 the vapours from the boiling are constantly precipitated by the play^ 

 of a fan. The tower contains a filter of coke, constantly moistened 

 by a stream of water. The aspirated vapours are in great part 

 condensed owing to the freshness of this water ; they then pass with 

 it into the drain. After twelve hours the vats are opened, the 

 floating fat removed, in the proportion of 10 to 20 per cent accord- 

 ing to the nature of the debris, then the bones and the flesh com- 

 pletely disintegrated. The liquors from the boiling are drained 

 through special piping into two large tanks. The tallow, as it 



