168 ON THE USE OF 



ficid necepsniy to be mixed witli the bones, it will be better 

 to inquire into the nature and properties of the substances we 

 propose mixing- tog-ether. 



Sulj)liuric acid, or oil of vitriol, as it is more frequently 

 termed, consists of the imion of two parts by Aveiglit of 

 sul|)hur with three of oxyg-en g-as ; and its strength depends 

 on its purity and freedom from water, for which it has a 

 remarkable affinity, so much so that, if ex])osed to the nir, it 

 will quickly absorb water from the atmosphere. Its relative 

 weakness, therefore, is owing- to the quantity of water mixed 

 with it. In speaking- of sulphuric acid, I must be under- 

 stood to mean in its concentrated state, possessing- a specific 

 g-ravity of from 18.45 to 18.50. And it should be borne in 

 3nind, in purchasing- the acid, that 50 lb. of the above 

 is at least equal to 60 lb. of the specific g-ravity of 17.14, 

 and therefore, if the weaker acid be used, its quantity 

 must be increased in proportion to the diminution of its 

 streng'th. 



On applying- the vitriolized bone to the tongue, we find 

 that it tastes both sour and sweet. The sourness arises, 

 probably, from the phosphoric acid, and the sweetness from 

 the g-elatine sug-ar, which is formed b}^ the action of the 

 acid on the g-elatine, converting- a substance very difficult of 

 decomposition into one readily soluble, and which can be 

 easily absorbed by plants. When concentrated acid is 

 mixed with a quarter of its weig-ht of water, the tempera- 

 ture of the mixture is raised to 300°, and boils away at a 

 great rate. The action of this heat on the animal part of 

 the bones renders it of a dark colour; but if a small quan- 

 tity of acid only be employed, the mixture is white, from 

 the carbonate of lime which then predominates. From an 

 averag-e taken from several analyses of bones of man and 

 various animals, the following- appears to be tolerably near 

 the mean : — 



Organic matter, consisting of gelatine, cartilage, and fat . . 34 



Phosphates of lime and magnesia 59 



Carbonate of lime 7 



loa 



Or, in rough numbers, the organic matter may be regarded 

 as forming one-third, and the earthy portions two-thirds> 

 Of course, if the bones are very fresli, the former will be 

 in larger proportion than one-third ; thus Mr. Hannam gives 



