198 ACID OR BI-PHOSPIIATE OF LIME. 



and of the earthy jjhosphate, while they will also be more susceptible of 

 l^peedy deconijjosition when buried in the soil.* 



In solutions of common salt and of sal-ammoniac, the earth of bones 

 is also slightly soluble, and cases may occur where the presence of 

 these com{)ounds in the soil may facilitate the conveyance of the earthy 

 phosphate into the roots of plants. 



B. Acid or B'l- Phosphate of Lime. — When burned bones are reduced 

 to powder, and digested in sulphuric acid (oil of vitriol), diluted with 

 once or twice its weight of water, the acid combines with a portion of the 

 lime, and forms sulphate of lime (gypsum), while the remainder of the 

 lime and the whole of the phosphoric acid are dissolved. The solution, 

 therefore, contains an acid phosphate of lime, or one in which the phos- 

 phoric acid exists, in much larger quantity than in the earth of bones. 

 The true bi-phosphate, when free from water, consists of 71i of phos- 

 phoric acid, and 28i of lime. It exists in the urine of most animals, and 

 is therefore an important constituent of liquid manures of animal origin. 



If the mixture of gypsum and acid phosphate, above described, be 

 largely diluted with water, it will form a most valuable liquid manure, 

 especially for grass land, and for crops of rising corn. In this liquid 

 state, the phosphoric acid will diffuse itself easily and perfectly through- 

 out the soil, and there will speedily lose its acid character by combining 

 with one or other of the basicf substances, almost always present in 

 every variety of land. 



Or if to the solution, before it is applied to the land, a quantity of pearl- 

 ash be added until it begin to turn milky, a mixture of the phosphates 

 with the sulphatcy of lime and of potash will be obtained, or — if soda be 

 added instead of potash— of the phosphates with the sulphates of lime 

 and of soda; either of which mixtures will be still more efficacious 

 upon the land, thanihe solution of the acid phosphates alone. 



Or to the solution of bones in the acid, the potash or soda may be added 

 without further dilution, and the whole then dried up by the addition of 

 charcoal powder, or even of vegetable mould, till it is in a sufficiently 

 dry state to be scattered with the hand as a top-dressing, or buried in 

 the land by means of a drill. 



I have above alluded to the employment of bones in France and Ger- 

 many, for the manufacture of glue. For this purpose the broken bones 

 are digested in weak muriatic acid, by which the earthy matter is dis- 

 solved, and the gelatine left behind. The gelatinous skeleton is boiled 

 down for glue, and the solution of the bone earth is thrown away. This 

 solution contains a mixture of the acid phosphate of lime with chloride 

 of calcium, — and might be used up in any of the ways above described, 

 with manifest benefit to the land. The glue prepared by this method, 

 however, is said to be inferior in quality, and as the process is not adopts 

 ed in this country, the opportunity of making an economical application 

 of this waste material is not likely to be often presented to the English 

 farmer. 



' The relative value of crushed bones in these two states, is indicated by the price of the 

 unboiled being about 7 guineas, while ihat of boiled is only about 4 guineas a ton. 



t This word has already been used and explained--it is applied to potash, soda, ammonia, 

 lime, magnesia, and other substances, which have the properly of combining with acids (sul- 

 phuric, nitric, &c.) and of thus neutrcUiziiig them, or deprivlT-^ them of their acid qualities 

 and effects. 



