Flesh.—Dried flesh forms u highly nitrogenous manure, and bids fair to assume a place in the market. It is principally derived from the refuse obtained in preparing Liebig's " extractuai carnis," samples of which have shown 11-12 per cent. of nitrogen. In this country, horse-carcases are often dissolved in sulphuric acid, and applied as a manure ; but their qualities are not superlative.
Blood.—Tho proportion of nitrogen contained in dry blood is very considerable, reaching 15 per cent. in thoroughly dried samples ; but it is so difficult to remove even a portion only of the water, that its use is restricted to narrow limits, except as an ingredient added to manufactured manures.
Guano.—It is unnecessary to repeat the meaning of the word "guano," or a description of the material known by this name ; but it is important to remark that the constitution of guanos is quite as varied .as that of any other mineral phosphate. The nature of a guano seems to depend principally upon the climatic conditions under which it accumulates. The dry atmosphere of the Peruvian coast favours the formation of a nitrogenous guano ; whereas similar deposits in moister climates lose all their ammonia, by decomposition and evaporation, and consist principally of phos phates insoluble in water ; though, when removed before much decomposition has had time to ensue, they contain also a certain amount of nitrogen.
Phosphatic guanos cannot be used in a raw state, and are employed only in the same way as coprolites, or other mineral phosphates, in the manufacture of superphosphate. They will therefore be described under that head (see p. 1259).
By far the greatest proportion of the nitrogenous guanos, and certainly all the best of them, have come from Peru, or the islands on its coast. The most valuable has been the Chincha Islands variety, containing about 13,* per cent. of nitrogen, and the same amount of phosphoric acid. This was almost entirely used in a raw state, but the deposits have long since been exhausted. Following this, came other high-class kinds, such as Ballestas, containing 12l per cent. nitrogen, and a similar proportion of phosphoric acid ; Macabee, with 11 per cmit. of nitrogen, and 12i per cent. phosphoric acid ; and Guanapi, yielding 10 per cent. of nitrogen, and Fit per cent. of phosphoric acid. But
these also are fast disappearing, and are being replaced by still lower-class articles : such are Pabillon, having nearly 9 per cent. of nitrogen, and almost 14 per cent. of phosphoric acid ; Inde pendencia Bay, with scarcely 8 per cent. of nitrogen, and 104 per cent. of phosphoric acid ; Huanillos, 7i per cent. of nitrogen, but over 14 per cent. of phosphoric acid ; Punta de Lohoe, not reaching 6 per cent. of nitrogen, and containing nearly 18 per cent. of phosphoric acid ; and some from the Lobos islands, giving little more than per cent. of nitrogen, while the phosphoric acid rises above 20 per cent. A very different species of Peruvian guano is the Angamos, which is freshly deposited, and obtainable only in small quantities. It coutains almost 4 per cent. more nitrogen than even the Chlncha Islands variety, with but 9 per cent. of phosphoric acid. The above figures distinctly indicate the extent to which guanos from the same country and climate differ in com position. The percentage of water varies also from 8 to 29 per cent. Most of these guanos contain a certain amount of all the elements essential in a good manure, besides the preponderating phos phoric acid and nitrogen. As much of the phosphoric acid present is combined with bases, in the form of phosphates which are insoluble in water, their effect upon the crop will be hastened by treating them with sulphuric acid, which possesses the property not only of rendering soluble much of the insoluble phosphate, but also of fixing the volatile carbonate of ammonium, and converting the uric acid present into ammonia. In applying crude guano to the soil, a considerable amount of ammonia will be evaporated and lost, unless the guano be completely covered with earth. This is prevented in a great measure by the treatment with sulphuric acid. Yet another advantage derived from dissolving the guano in sulphuric acid is that the great hygroscopic properties of the acid render the manure dry and powdery ; this is especially advantageous when the sample of guano is very damp and sticky, as is generally the case. Very large quantities of guano are pre pared in this way in Germany, and sold by analysis, on a basis of nitrogen equal to 9 per cent. of ammonia, and about 25 per cent. of phosphates, 20 of which are soluble.