This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1899 edition. Excerpt: ...sulphate of ammonia is said to contain 24 units of ammonia or i9f units of nitrogen. The price per unit of ammonia is therefore ?10 2s. 6d.-r-24 = 8s., 5d.; while a unit of nitrogen costs ?10 2s. 6d.-h 19I = 10s. 3d. Similarly, the nitrate of soda is said to contain 15-65 units of nitrogen, or 19 units of ammonia; the price of the former being nearly 9s. 1 id. per unit, that of the latter 8s. 2d. per unit. In actual working, this system of estimating the cost per unit is very simple and helpful in comparing the relative costs of manures; for by it, and taking into account also the suitability of two manures for any given purpose, we can decide on their comparative economy. It will be easily realized that nitrogen is sometimes cheaper in one manure, sometimes in another, according to variations in the market quotations. Very often one comes across a tendency to buy a manure because it is at a low price per ton; but this may not be the cheapest manure. The cost per unit of nitrogen, or whatever of value the manure contains, may be greater than that in another manure at a higher price per ton. At the prices mentioned above, it will be seen that nitrogen in sulphate of ammonia is slightly more expensive than in c nitrate of soda. The reverse of this is often the case, owing to variations in prices; and, indeed, for some years sulphate of ammonia has been generally the cheapest source of nitrogen in the market--the price per unit of nitrogen having been as a rule lower (sometimes as much as 20 per cent. lower) than in any other manure supplying nitrogen in a condition equally ready for the use of crops. Impurities And Adulterants. Good samples of sulphate of ammonia generally contain little impurity except moisture, with a very small amount of... Это и многое другое вы найдете в книге The utility of sulphate of ammonia in agriculture (James Muir)