MANURE FEOM ANIMAL WASTE. 263 



M. A. Louis has organized at Caen an interesting application 

 of Aime Girard's process, for the destruction and disinfection of 

 carcases and animal debris by means of sulphuric acid, Louis uses 

 likewise slaughter-house and butchery residues. In 1889, his first 

 year of working, Louis made 483 tons of manure containing 16 to 

 18 per cent of phosphoric acid, 2 per cent of nitrogen, and 5 per 

 cent of potash; in 1900 his manufacture had risen to 930 tons. 



Louis' method of working consists in dissolving the animal 

 matter in sulphuric acid, and saturating the pasty mass so obtained 

 by phosphate of lime in powder, which finally yields a nitrogenous 

 phosphate. 



Commercial Meat Meal. — The meat meal of commerce is a 

 mixture of meat meal and bone meal. It is made from the waste 

 from the manufacture of extract of meat ; in South America also 

 from the carcases of animals, knackers' meat, by steam heating, 

 drying, and grinding. The greater part of the meat meal is 

 marketed as Fray Bentos guano : it contains 6 "5 to 7'5 per cent 

 nitrogen and 17'18 to 11*14 of phosphoric acid. Finally, meat meal 

 is rendered soluble by sulphuric acid. 



Horn. — Horn is met with under different forms in commerce. 

 The horns of ruminants are generally very pure, and contain dry 

 and free from bone 13 to 14 per cent of nitrogen. Whalebone 

 waste, when not in too small fragments, is almost equal in value. 

 Horn and whalebone turnings and shavings are less esteemed, 

 because they are generally mixed with wood shavings and other 

 sweepings of the workshop. Their nitrogen content rarely reaches 7 

 to 8 per cent. Hoofs are richer in nitrogen than ground horn. They 

 generally consist of pure horn ; on the other hand they are often wet 

 and soiled by excreta. Hair, wool, wool rags, old felt, and feathers 

 have the same value as horn. But great care must be taken in 

 buying, because it is difficult to determine the impurities of all sorts 

 which may be mixed therein. In the pure state they contain 11 

 to 13 per cent of nitrogen ; as sometimes delivered to the factories 

 they only contain 5 to 6 per cent. Wool dust, from the combing 

 and spinning of wool, is not of a nature to inspire much confidence. 

 It rarely contains 6 per cent of nitrogen, often only 3*4 per cent of 

 that element. To serve as manure ail these materials must be 

 reduced to a fine powder. But even when apparently dry they are 

 so tenacious that it is impossible to grind them. Wool dust itself 

 already in a fine powder cannot be ground finer. That is why they 

 are submitted to a special preparation, which consists in roasting 

 them or in heating them in a closed vessel. To roast horn, it is 

 spread on a cast-iron plate or in a shallow pan, which is heated 

 without interruption so as to avoid overheating and loss of nitrogen. 

 The matter assumes a dark colour, and when it is cool it is brittle 

 and easy to crush. When it is a case of horn turnings, it suffices to 



