FLUORIDE OF CALCIUM IN WATER. 147 
the age of bones, and of the rocks containing them, by the per-centage of fluorine 
in the former.* This idea, however, is certainly unwarranted. In the bones of 
five fossil animals, including the Plesiosaurus and Ichthyosaurus, GrrARDIN and 
Preisser found from one to two per cent. of fluoride of calcium ;} whilst in those 
of the recent ox, BERzELIus found nine per cent.{ In the ancient bones there was 
thus, instead of a much higher per-centage, seven per cent. less of fluorine than in 
the recent bones. Many other objections might be made to Mr MIppLETON’s view. 
Those who deny the existence of fluorine in recent bones, consider the whole 
amount of that element found in ancient buried ones, as in some way or other a 
product of fossilisation. According to those, on the other hand, who affirm the 
presence of that element in recent organisms, only a portion, at most, of the fluo- 
rine found in osseous remains has been added since they ceased to be parts of 
living animals. It is impossible, however, to separate the two questions. We 
have no data from which to determine whether or not the bones of an extinct 
animal contained fluorine during its life, and, if it did, how much was present. 
It will be sufficient, therefore, if I consider what progress has been made in an- 
swering the one question, How does fluoride of calcium come to be present in 
bones, either recent or fossil ? 
Three replies have been proposed to this query. 1st, That of Dr FALconer, 
already referred to, which, taking for granted that fossil bones contain more fluo- 
rine than they possessed whilst parts of living animals, assumes, or rather sug- 
gests as possible, that phosphate of lime has been transmuted into fluoride of 
calcium.j 2d, That of Liesie, which, going on exactly an opposite assumption, 
takes for granted (if I understand him aright) that bones of living antediluvian 
animals contained the same proportion of fluorine which we find in their fossil 
remains; and refers its greater abundance in these, either to its having been 
present in larger quantity in the food of their living possessors, than it is in that 
of existing animals, or to its having been appropriated to a larger amount from 
it.|| The third is that of Mr MippLEeron, who supposes every bone to possess 
normally two per cent. of fluoride of calcium, and considers all above that which 
a fossil bone contains, as added to it whilst buried in the earth, by the infiltra- 
tion of water containing that salt held in solution by some unknown solvent. 
It is unnecessary to discuss the first and second propositions referred to. It 
is impossible, in the present state of our knowledge, either to prove or to disprove 
them. The idea of transmutation of a phosphate into a fluoride, was doubtless 
suggested solely because there seemed no other way of accounting for the accu- 
mulation of fluorine, and will be abandoned, if it shall appear that recognized 
* Quarterly Journal of Geological Society, vol. i, p. 216. 
7 Annales de Chimie, 1843, pp. 370-78. { Ibid., t. lxi., p. 257. 
§ Literary Gazette, 1843, p. 779. 
|| Chemistry of Agriculture, 3d edition, p. 123. 
