The value of soot as a manure depeuds upon the ammonium salts which it contains, as well as upon its beneficial effect on the texture and colour of the soil, and its power of diminishing the ravages of slugs and small snails upon a young crop. In various samples which from time to time have been submitted to analysis the percentage of nitrogen present has been found to vary within very wide limits, from 0·5 to 7 per cent., and it is usually stated to be present in the form of ammonium sulphate; actually it occurs for the most part as ammonium chloride.