722 The American Naturalist. [August, 
enough of the constituents to find in it, as well as in the mylo- 
don bone, the ratio between the fluorine contained in the bones 
and the theoretical quantity which an apatite having the 
same proportion of phosphoric acid would contain, as recom- 
mended by M. Carnot in the Ann. des Mines, 1893. 
Deducting the moisture and organic matter, therefore, we 
should have the following partial composition of the ash of 
the human bone :— 
Iron (and alumina) phosphate, ‘ : : 17.34 
Lime (Ca 0O), . ; ; ; : ; 37.25 
Total phosphoric acid, i : i : 27.69 
Fl (fluorine), . ; $ ; : 0.51 
Or Ca Fl (calcium fluoride), . i ; i ; 1.03 
The analyses are here re-arranged so as to permit of compar- 
ison with those tabulated by M. Carnot :— 
| a) 
a | E Eri = g% o 
2 iy E s |253 
E | Se o $ or EB A 
Ash o | ae E E 3 Jags 
a. | Se Bois 3 gah 
T ee es E 
o |3 = 5 2 
| 3 a = 
a) Clee Oe Pe 
| 
Mylodon 22.55 | 7.75 | 26.59 | 028 | 237 | 9.12 
AUSSIE ETA HAE | | 
| 
Vaan tone 21.43 | 650 | 20.77 | 088 | 1.85 | 0.20 
In the present instance the fluorine was determined by the 
method recommended by M. Carnot with no essential modifi- 
cations. This method differs from others mainly in the com- 
position of the precipitate produced. The process, in brief, 
consists in decomposing the substance mixed with silica (free 
from fluorine) with concentrated sulphuric acid which has 
been freed from fluorine by heating with silica, passing the 
silicon fluoride gas evolved through dry tubes unto a solution 
of fluoride of potassium, and precipitating the fluo-silicate of 
