90 Dr Rees on Fluoric Acid in Animal Matter. 



traction, and by greater care employed in the collection of the 

 boracic vapour. In 1833, about 650,000 Tuscan pounds were 

 obtained ; in 1836, two millions and a half. 



But it appears to me that the powers and riches of these 

 extraordinai'y districts remain yet to be fully developed. They 

 exhibit a great number of mighty steam-engines, furnished 

 by nature at no cost, and applicable to the production of an 

 infinite variety of objects. In the progress of time, this vast 

 machinery of heat and force will probably become the moving 

 central point of extensive manufacturing establishments. The 

 steam, which has been so ingeniously applied to the concen- 

 tration and evaporation of the boracic acid, will probably here- 

 after, instead of wasting itself in the air, be, employed to move 

 huge engines, which will be directed to the infinite variety of 

 production which engages the attention of labouring and in- 

 telligent artisans ; and thus, in the course of time, there can 

 be little doubt, that these lagoons, which were fled from as ob- 

 jects of danger and terror by uninstructed man, will gather 

 round them a large and intelligent population, and become 

 sources of prosperity to innumerable individuals through count- 

 less generations. 



On the Supposed Existence of Fluoric Acid, as an Ingredient 

 in certain Animal Matters. By G. O. Rees, M. D., F. G. S. 

 &c.* 



In the year 1802, Morichini published a paper, in which he 

 declared fluoride of calcium to be an ingredient in human 

 teeth. He was led to examine that substance from having 

 succeeded in detecting the fluoride in a specimen of fossil 

 ivory. Mons. Gay Lussac repeated these experiments ; and 

 in the 55th volume of the " Annales de Chimie," he states, 

 that the fluoride exists in recent as well as in fossil ivory ; and 

 that he had also succeeded in detecting it in the tusks of the 

 Avild boar. Fom'croy and Vauquelin subsequently published 

 a memoir in the 57th volume of the " Annales de Chimie," 

 in which they positively denied the existence of fluoride of 



'•' From Guy's Hospital Reports, No. ix. October 1839, pp. 38), &c. 



