and the Enamel of Teeth. 267 



even in the latter case, we observed, in a very remarkable 

 manner, the effects of the fluoric acid upon the glass when 

 these mixtures were treated as above mentioned. These 

 effects were even much more sensible than those produced 

 by the fossil ivories of the canal of Lourque and of Argen- 

 tend ; which shows that the filiate of lime does not exist in 

 a greater proportion than three or four -per cent. 



Those who have announced the discovery of the fluoric 

 acid in ivory, do not assert that this substance was found ready 

 formed in it, although they recollect that formerly Rouelle 

 tried in vain to extract phosphorus from it ; yet upon treat- 

 ing 300 grammes of it in the same manner in which bones 

 are treated for the purpose of obtaining phosphorus from 

 them, we obtained 15 grammes of very pure phosphorus 

 in a very pure state. This quantity of phosphorus is nearly 

 the same as that obtained from bones ; and it is probable 

 that we might have bad still more, if the retort had not bro- 

 ken before the operation was entirely finished. 



If by the first operation to which we submitted the fresh 

 ivory we had not perceived any vestige of the fluoric acid, 

 the circumstance which we are about to relate proves that 

 it contains phosphoric acid in abundance, and probably as 

 much as bones do. 



The pungent smell which is disengaged at the moment 

 when the sulphuric acid is mixed with calcined new ivory, 

 cannot be regarded as a certain mark of the presence of the 

 fluoric acid, because-there is produced in this case a degree 

 of beat So considerable as to volatilize with the water a small 

 quantity of sulphuric acid : besides, this vapour manifests 

 itself also during the mixture of the sulphuric acid with, 

 such bones, where the presence of the fluoric acid is not ad- 

 mitted. 



Several chemists in Paris, having repeated the same cxp?* 

 riments upon ivory, obtained results nearly similar to ours. 



Although we have not found fluoric acid in new ivory 

 nor in the enamel of teeth, as announced by M. Morichini, 

 it is nevertheless clear, that such fossil ivories, of whatever 

 country they are, as have lost their animal matter, contain 

 some hundredths of fluoric acid. This truly singular cir- 

 cumstance scema to indicate that these substances are, after 



cumstance 



