204 M. Douovan on the Preparation of Phosphorus. 



an imperial pint measure of ordinary urine, according to the 

 analysis of Berzelius, there are but 41 grains of phosphates, 

 while there are nearly three times as much of other salts, all 

 capable of precipitating acetate or nitrate of lead. Thus but a 

 small part of the precipitate is available for the purpose, and the 

 retort is uselessly occupied with substances which contribute 

 nothing. 



From bones, it is true, we procure phosphorus more easily, 

 and in greater quantity ; but so long as we follow the process 

 given in chemical works, the details, as already shown, are ex- 

 tremely troublesome. On this account I have sought for a 

 more simple method. 



Bones are procurable in various commercial states ; we have 

 them solid ; ground to a coarse powder between crushing rollers, 

 for manure ; distilled in close vessels for carbonate of ammonia, 

 and the residual charred bone afterwards ground to a powder, 

 well known under the name of bone-black ; or in small particles 

 obtainable from the lathe of the bone-turner. In all these states, 

 bones afford phosphate of lime ; but there are other sources, one 

 of the most abundant of which is the horn of certain animals. 

 The horns of the Stag {Cervus elaphus) and of the Fallow-deer 

 (Cervus dama), and perhaps those of the whole class of Cervidae, 

 furnish phosphate of lime abundantly; but those of the Ox, Ram, 

 Goat and Chamois, scarcely contain any. The commercial repre- 

 sentative of the horn of the Stag or Fallow-deer is known under 

 the name of shavings of hartshorn, and may be procured in great 

 abundance. 



Many analyses of bone have been published by chemists ; but 

 their results are so utterly discordant, owing to the different 

 states in which the bones were examined, that I could not collect 

 from them the ratio of salts which constitute the earthy basis. 

 To arrive at the required information, I made many trials of 

 recent bones, containing theirnatural quantity of fat and moisture, 

 and obtained the following average results. Recent ox-ribs, from 

 which the flesh had been carefully scraped, when calcined to 

 whiteness, afforded 37*14 per cent, of earthy matter. Recent 

 sheeps^ bones (from the leg), when similarly treated, returned 

 38*71 per cent. It may be concluded then that a mixture of 

 dense, recent bones, with which no pains have been taken to 

 remove fat or moisture, will afford about 38 per cent, of earthy 

 salts by incineration. A very porous ox-bone gave but 21 per 

 cent. Neumann obtained 40*6 per cent. Fourcroy and Vau- 

 quelin give 49 as their result. Berzelius states his product to be 

 61 per cent. Von Bibra quotes 66*78 per cent. These great 

 differences arise from the variable ratio of fat and moisture in 

 the bones^ which however I took no pains to remove. 



