1895.] Fluorine as a Test for the Fossilization of Animal Bones. 723 
potassium so produced with alcohol, which precipitate is col- 
lected on a tared filter dried and weighed. The decomposi- 
tion is effected in a dry flask ata temperature of about 100° C 
and the current of dry air is passed through the apparatus 
during the operation, which lasts a couple of hours or more. 
I examined the precipitates under the microscope in order to 
be certain of their character, and observed the small isometric 
forms—combinations of cubes and octahedrons—under which 
silicofluoride of potassium appears. 
The analyses of the human bone and mylodon which you 
had made formerly and have handed me, show that the speci- 
mens differed in several respects from those you furnished me. 
The composition of the mylodon bone does not vary so very 
much in its essential constituents from that I have analyzed, 
but the human bone contained 22.59 per cent. of silica. De- 
ducting that figure from the total, and recalculating, we have: 
Loss on ignition, ‘ : : i -o 1o 
Lime, ; : ee ees . 83.59 
Phosphoric acid, : oon i : : 22.57 
This makes the proportion of lime about six per cent. greater 
than in the specimen I analyzed, while the phosphoric acid is 
only some two per cent. higher. In both cases that latter con- 
stituent is present in much smaller proportion than is usually 
given for phosphoric acid in human bones. (See Fremy, 
Encyclopedie Chimique T. IX, p. 603, where phosphoric acid 
is as high as 58 per cent. of the ash or total mineral matter). 
Moreover, the percentage of ash is higher than is usual in 
human bones. A listin Watts’ Dictionary, article Bone, gives 
the percentage of ash in such bones as below 70 per cent., rang- 
ing from about 50 to 70, while in the present case the ash is 
about 75 per cent. 
Iam 
Very truly yours, 
(Signed) R. L. PACKARD. 
It is always to be remembered throughout this paper, both 
in the investigations of myself and Dr Packard, as well as in 
