218 BONES. 



although at a somewhat higher price than that given 

 for ordinary bone-dust, and the manufactory at 

 Strehla has received for many years past more ap- 

 plications than it could satisfy. 



That practical experience is right, follows as a 

 matter of course, and it now remains for science to 

 disclose the reason of this unexpected operation. I 

 believe it to be this. In crude bone every individ- 

 ual particle of gelatine is surrounded with an almost 

 impenetrable covering of bone-earth, that prevents 

 the insinuation of water and air, more particularly 

 as the fat, with which bones are interpenetrated, of- 

 fers resistance to water ; hence putrefaction, espe- 

 cially in coarser fragments, can only advance by ex- 

 tremely slow stages from the exterior to the interior 

 of bones. By treating bones with steam at a high 

 pressure, which thoroughly penetrates their tissue, 

 the fat and a part of the gelatine is extracted, and 

 their mass now becomes so porous, that the moisture 

 of the earth can force its way into the interior, and 

 cause the putrefaction of the gelatine that is situated 

 there. The dissolution of the bone-earth now goes 

 on in close accompaniment with the putrid decom- 

 position of the organic matter. Over and above this, 

 more rapid solubility is promoted by the very mi- 

 nute state of subdivision, since the Strehla bone- 

 dust is very much more finely levigated than the 

 best specimens of other varieties that are met with 

 in commerce. 



The steaming of bones has recently attracted the 



