Phosphatic Materials used for Agricultural Purposes. 29 



constitution of pure bones is well known, and affords a ready 

 means for checking such errors. It has appeared to me more 

 desirable to prove this assertion by the results of direct investiga- 

 tions of my own than to base it upon calculations derived from 

 published analyses of bones. 



With this view I prepared samples of ox .and horse bones, 

 selecting the cleanest and hardest. The bones, after being care- 

 fully scraped, were broken into small pieces, which were soaked 

 in cold distilled water for a week, in order to remove any 

 soluble salts. After that time they were reduced to powder ; 

 this was repeatedly washed with distilled water. The bones thus 

 purified were next burned in a platinum capsule at a moderate 

 heat, the ash was again washed repeatedly with distilled water, 

 then moistened with carbonate of ammonia in order to convert 

 any caustic lime which might have been produced during burn- 

 ing into carbonate. Direct experiments, however, showed that 

 the heat employed was not sufficiently strong to drive off 

 carbonic acid. 



Although both the bones and their ash were washed with a 

 great deal of water, it was found impossible completely to remove 

 the alkalies. Even the hardest bones contain some potash and 

 soda. By long washing, the amount of alkalies may be dimi- 

 nished, but hitherto I have not been able to obtain a bone-ash 

 perfectly free from alkalies, though I have washed small quantities 

 for longer than a fortnight on a filter. 



Prepared in this way, the ash of horse and ox bones, in a 

 perfectly dry state, was found to consist of: 



Composition of the Ash of 



The ash of the ox-bones was not washed quite so long with 

 water as that of the horse-bones, and contains for this reason 

 rather more potash and soda. These results are here stated as 

 they have been actually obtained in the analysis. In bone-ash, 



