374 
C/irmica! Composition and Conimrrcial Valnr of 
The same bonc-asli was likewise submitted by myself and by 
Mr. Sibson to an analysis, in which the ordinary precipitation 
method was adopted, and the following results were obtained : — 
Voelckcr. Sibson. 
Water G-34: (i-35 
Organic matter , .. .. .'i-SS .'5-09 
Phosphates 79-03 76-70 
Carbonate of lime 3-18 5-34 
Alkaline salts 2-68 2-52 
Insoluble siliceous matter 8-43 9-39 
103-04 103-39 
In explanation of these results, I may observe that the excess 
in the analyses is principally due to the circumstance that all the 
lime which is not united with phosphoric acid is introduced 
here as carbonate of lime. The alkaline salts likewise help to 
increase the excess, for in reality the greater part of the alkalies 
occurs in bones as such, or in union with phosphoric acid, the 
total amount of which is mentioned in the analyses already. 
The direct weight of the thoroughly-heated residue, which is 
obtained on evaporation of the liquid from which the phosphates 
and the lime have been removed, therefore gives the alkalies 
too high. 
In reality commercial bone-ash contains seldom more than 
If to 2 per cent, of carbonate of lime, and the lime which is not 
in union Avith phosphoric acid, nor with carbonic acid, must 
therefore be present in some other state of combination. Some 
of it, no doubt, is present as fluoride of calcium and some as 
silicate of lime ; silicate of lime is not a normal constituent of 
bone, but it is produced when bones are reduced to ash in large 
heaps. The silica, Avhich is usually attached to raw bones in 
the shape of fine sand, at a high temperature, decomposes some 
of the carbonate of lime which bones naturally contain, and gives 
rise to silicate of lime. 
It might, perhaps, be supposed that bone-ash contained some 
caustic lime, arising from the high temperature at which the 
bones are sometimes burned. But this is not generally the case, 
as I have proved repeatedly by determining the amount of car- 
bonic acid in the natural sample, as well as after having moistened 
and heated it with carbonate of ammonia. Had there been any 
caustic lime present in the bone-ash, the portion treated with 
carbonate of ammonia would have yielded a larger amount of 
carbonic acid than the sample analysed in its natural state, 
whereas both furnished almost identical results. 
Again, commercial bone-ash contains a little sulphate of lime, 
but its quantity is quite insignificant. 
In all the following analyses, phosphoric acid and lime have 
