368 Chemical Composition and Commercial Value of 
The first, analy sis, more especially, has evidently been done in 
a very careless manner, for bone-ash prepared from pure bones 
does not contain so high a pcrcentajje of phosphate of lime as 
this sample of the commercial article is rejjortod to contain. 
The proportion of charcoal, moisture, and sand — three matters 
not properly belonginof to pure bone-ash, amount to 10 per cent, 
in round numbers. Deducting these accidental constituents, and 
calculating the results for pure bone-ash, the latter would contain 
no less than 97'66 per cent, of bone-earth. It is hardly con- 
ceivable how such absurd results as those contained in the first 
.analvsis can be committed to paper by an analytical chemist. 
If these were solitary instances I would take no further notice 
of analyses the incorrectness of which is proved by abundant 
internal evidence. But unfortunately this is not the case. 
Bone-ash is usually sold by importers at a price depending upon 
the percentage of phosphate of lime in it, and hence it is not 
the interest of dealers to have the determination of bone-earth 
made by a chemist who states the amount correctly, but rather 
to employ an analyst who, adopting an expeditious and incorrect 
method, makes the percentage of phosphates 3, 4, and even 6 
per cent, higher than it is in reality. The importance of this 
subject has led me to examine minutely the composition of pure 
and of commercial bone-ash. 
The mineral portion of pure bones or pure bone-ash has 
been repeatedly examined by various chemists. The more 
recent researches by Professor Heintz, of Berlin, deserve espe- 
cial notice. According to Heintz, the phosphate of lime present 
in bone-ash is a combination of 3 equivalents of lime and 1 
equivalent of phosphoric acid ; its formula consequently is 
3 C O -I- P Oj. Although some chemists still retain the older 
formula 8CO-i-3P05 assigned to bone-earth by Berzelius, 
most agree with Heintz in considering the chief constituent of 
bone-ash to be the tribasic phosphate of lime. In the analyses of 
human and other bones, the same gentleman obtained a certain 
proportion of lime, which was neither united with phosphoric 
acid, as tribasic phosphate, nor with carbonic acid. This excess 
of lime is calculated in Heintz's analyses as fluoride of calcium. 
Thus he states in one place that human bones contain 3"52 per 
cent, of fluoride of calcium ; in another analysis he gives 3 82 
per cent, of fluoride of calcium in bones dried at 212° Fahr. It 
should be mentioned, however, that no direct fluorine determina- 
tion has been attempted, but that the result has been obtained 
by calculation. Every chemist is acquainted with the fact that 
bones contain small quantities of fluorine ; but, at the same time, 
considerable difficulty is experienced occasionally in obtaining 
with recent Ijones a deep etching u])on glass, even if large 
