220 BONES. 



probable that in these cases the soil was already suf- 

 ficiently provided with azotized substances, and, on 

 the other hand, labored under a deficiency of phos- 

 phoric acid or lime. The latter, moreover, act benefi- 

 cially upon what are termed the mineral ingredients, 

 inasmuch as they render soluble such of these as by 

 themselves are wholly insoluble. An attempt has 

 been made in England to make burnt bones soluble, 

 in the same way as bone-dust, by means of sulphuric 

 acid ; and this mass, when mixed with ammoniacal 

 salts, furnishes an excellent substitute for bird-ma- 

 nure, which, under the name of artificial guano, has 

 already met with very extensive application. 



Sugar-refuse is a bone-coal that has served in su- 

 gar-refineries to deprive brown sirup of its color. It 

 sometimes contains azotized substances in but small 

 quantity, when only the albuminous constituents of 

 the sugar have been left behind in it ; and again 

 in very large amount, when blood has been simulta- 

 neously made use of in the process of refining. A 

 sugar-refuse of the last description, containing 8 to 10 

 per cent, of nitrogen, now brings in France far high- 

 er prices as a manure than fresh bone-black. Sev- 

 eral specimens examined in Saxony contained only 

 1| to 2 per cent, of azote, and produced no consider- 

 able effect on the land. As a means has now been 

 discovered, in manufacturing sugar, by which the 

 bone-black already used can be revivified, that is, 

 made fit for renewed employment, whereby it ac- 

 quires a higher pecuniary value than could be ob- 



