_Night-Soil and Poudrette._--The value of night-soil, which is well known, depends partly on the urine, and partly on the faeces of which it is formed. Its disagreeable odour has prevented its general use, and various methods have been contrived both for deodorising and converting it into a solid and portable form. The same difficulties which beset the conversion of urine into the solid form occur here, and in most of the methods employed the loss of ammonia is great. It is sometimes mixed with lime or gypsum, and dried with heat, and sometimes with animal charcoal or peat charcoal. The manufacture of a manure from night-soil, called "poudrette," has long been practised in the neighbourhood of Paris and other continental towns. The process employed at Montfaucon and at Bondy is very simple. The contents of the cesspools are conveyed to the work in large barrels, which are then emptied into tanks capable of containing the accumulation of several months. When filled they are allowed to stand for some time, during which the smell diminishes and the contents become nearly dry. The residue is then dug out and mixed with ashes, dry loam, charcoal powder, peat, peat-charcoal, saw-dust, and other matters, so as to deodorize it, and render it sufficiently dry for transport. Its general composition may be judged of from the subjoined analyses of samples from different places:-- Montfaucon. Bondy. Dresden. American. Water 28.00 13.60 19.50 39.97 Organic matters 29.00 24.10 20.80 20.57 Phosphates 7.65 4.96 5.40 1.88 Carbonates of lime and } Magnesia, alkaline } 7.35 14.14 11.30 7.63 salts, etc. } Sand 28.00 43.20 43.00 29.95 ------ ------ ------ ------ 100.00 100.00 100.00 100.00 Ammonia 1.54 1.98 2.60 1.23 These analyses shew sufficiently the extent to which the animal matters have been mixed with valueless driers, the second and third samples containing considerably more than half their weight of worthless matters. _Hair, Skin, and Horn._--The refuse of manufactories in which these substances are employed, are frequently used as manures. They are highly nitrogenous substances, and owe their entire value to the nitrogen they contain, their inorganic constituents being in too small quantity to be of any importance, wool and hair having only 2 per cent, and horn 0.7 per cent of ash. In the pure and dry state, and after subtraction of the ash, their composition is,--