Animals and the Elements in which they Live. 227 



mals ; and we have seen that this agreement is as close and 

 as complete throughout the types of Radiata, Mollusca, and 

 Articulata, as it is plain among Vertebrata, and the slight 

 difficulties to which we have alluded, must probably be re- 

 ferred to the present state of our knowledge respecting some 

 of them, rather than to a departure from this law in any of 

 their types. 



On the Presence of Fluorine in Blood and Milk. By GEORGE 

 Wilson, M.D., F.R.S.E. Communicated by the Author * 



In 1846 T announced to the Royal Society of Edinburgh, 

 that after finding that fluor spar was soluble in water, and 

 occurred in many natural waters, I thought it well to seek 

 for it in milk and in blood, and found distinct evidence of its 

 presence in both. The proofs, however, were not so decisive 

 as I could have wished, and the processes followed were 

 liable to objection from their complexity, and the possibility 

 of fluorine being introduced in some of the reagents em- 

 ployed. There was reason also to suspect, that even if 

 fluorine were present, it might be carried away by the con- 

 siderable volume of liquid employed in the treatment of the 

 blood and milk. 



This summer, accordingly, I have examined both of those 

 liquids on a much larger scale, and by a much simpler pro- 

 cess than formerly, and the results obtained have been so 

 satisfactory, that I have thought they would prove interest- 

 ing to the Section. 



In my former examination of blood, I obtained a good 

 result only when the serum was employed. This summer, 

 however, I have employed the fresh drawn blood of the ox, 

 exactly as it was furnished by the butcher. About 26 im- 

 perial pints, or three gallons of blood, were made use of. This 

 was obtained from diff^erent animals, in quantities of about 

 nine pints at a time, as this was as much as could be conve- 



* Read to the British Association, »t its Meeting in Edinburgh, August 6, 

 1850. 



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