1895.] Fluorine as a Test for the Fossilization of Animal Bones. 449 
gaseous state in a humid atmosphere in the sedimentary 
strata, we are obliged to conclude that it penetrated into these 
strata under the form of an aqueous solution. It is, therefore, 
to infiltration of water, that has, during the lapse of time, 
come in contact with these fossil bones, that we must attribute 
this increase of fluorine, as well as other chemical changes, 
like the fixation of oxide of iron, the fixation and more rarely 
the disappearance of carbonate of lime, the solution of phos- 
phate, etc. According to all appearance, the infiltrating 
water carries traces of fluorine in solution, and these traces have 
been fixed progressively on the phosphate of lime, by virtue 
of some sort of affinity which we may suspect, remarking 
that all crystallized phosphates of lime contain fluorine (or 
chlorine) in a constant quantity. But there are other proofs— 
the affinity of the phosphate of lime for fluoride or for chlor- 
ide of calcium ata high temperature has been demonstrated by 
the experiments made in connection with the synthesis of 
apatite, which synthesis was made first by Mons. D’Aubrée 
(by means of lime and chloride of phosphorus), then by 
Forschammer (by phosphate of lime and chloride of sodium), 
then by H. Sainte Claire Deville and Caron (by phosphate of 
lime and chloride of calcium). 
Experiments have been made to determine whether the 
same affinity was sensible in the cold and by the wet way; 
and if the phosphate of lime in modern bones could fix the 
fluoride of calcium in analogous conditions with those in 
which the fossil bones must have been (save and except the 
lapse of time and the degree of concentration of the liquids). 
Experiment No. 1.—A bone of a manatee (in fragments) was 
placed in 200 cubic centimetres of a solution of alkaline flu- 
oride diluted to the 50th part, containing 2 grams of carbonate 
of ammonia. At intervals of time, longer or shorter, frag- 
ments of this bone were taken out, carefully washed and dried 
and subjected to analysis for fluorine. The proportion of 
bone in the fluorine was originally ys of one per cent. After 
remaining fifteen days in this solution, had increased to 1.70 
per cent. After remaining a month in the liquid, it contained 
2.81 per cent, and after five months, 7.74 per cent. The pro- 
