288 Dr Daubeny on the Occurrence of Fluorine 



change in appearance from its normal state, while it had all the 

 tenacity of recent bone. It had, however, a slightly yellowish tinge, 

 and the cells between the plates were charged with a white substance 

 which, when examined, was found to consist of chloride and oxide of 

 magnesium. The following were its constituents : — 



Organic matter, 31*59 per cent.; phosphate of lime, 50"58 ; 

 carbonate of lime, 9*83; fluoride of calcium, 1*86 ; soda, 1"08 ; 

 chloride of sodium, 2*42 ; magnesia and chloride of magnesium, 

 3-50. 



Twelfth, Analysis of a portion of a recent skull — Organic mat- 

 ter, 33*43; phosphate of lime, 51*11; carbonate of lime, 10*31; 

 fluoride of calcium,* 1*99; soda, 1-08 ; chloride of sodium, 0*60 ; 

 magnesia and phosphate of magnesia,! 1*67. 



It is perhaps unnecessary to add more to these analyses than the 

 statement that they have been performed with great care, and that 

 to these, and congeneric inquiries, I have devoted some months ; while 

 pursued as they were in the Laboratory of University College, I had 

 the advantage of most able advice and assistance. + — I am, &c. 



J. MiDDLETON. 



LoN^DON, June 7. 1844. 

 — JPhilosopJiical Magazine No. 164, p. 14. 



On the Occurrence of Fluorine in Recent as well as in Fossil 

 Bones. By Charles Daubeny, M.D., F.R.S. 



Having, in the course of the preceding spring, paid a visit to the 

 deposit of compact phosphorite, which occurs in the province of 

 Estremadura in Spain, I was subsequently led to examine into the 

 chemical constitution of the mineral which forms the prevailing in- 

 gredient of the vein to which my inquiries had been directed. 



The results of my examination have already been reported in the 

 memoir communicated by my fellow-traveller, Captain Waddington, 

 R.N., and myself, to the G-eological Society, with respect to the 

 rock in question, and read at their meeting on the I7th of January 

 last ; from which it will be seen, that the mineral, although not 



* So far as an inference maybe drawn from qualitative indications, 

 the bone of a foetus of Q\ months, contains as great a proportion of 

 fluoride as that of an adult ; an interesting fact, and not, I believe^ pre- 

 viously noticed. 



t If none of the magnesia existed in the bone as phosphate, which 

 there is much reason to doubt, the phosphate of lime would be increased 

 about 1 per cent. ; and the fluoride of calcium would be, therefore, pro- 

 portionally diminished. 



I The results of MM. Girardin and Preisser's analyses of ancient and 

 fossil bones will be found in Phil. Mag. s. 3, vol. xxiv., p. 18. — Ed. 



