34 



Dr. R. D. Thomson on the History 



[Jan. 



killed, twelve hours elapsed between the two bleedings, 

 during which time it obtained no food : — 



SERUM. 



The globules have here it is true diminished at the second 

 bleeding, but so slightly, that we may attribute this cir- 

 cumstance to the unassimilated chyle which must have been 

 present in the system. In the former case, the animal 

 had been exhausted by previous depletions, and hence pos- 

 sessed no store from which the blood could derive even a 

 small portion of serum, as in the latter instance. 



Article V. 



History and Analysis of the Vanadiate of Lead. By 



Robert D. Thomson, M. D. 



" »v 



When the history of the brown lead mineral of Zimapan is 

 considered, it appears not a little remarkable that Vana- 

 dium should have remained for nearly thirty years in obscu- 

 rity, after the idea of its existence was suggested. But the 

 discovery of the metal within the last few years, is a strik- 

 ing proof of the improvement in chemical analysis, and of 

 the assiduity and careful scrutiny with which the whole 

 material world is in progress of being examined. 



Humboldt, under the date of 14th November 1803, pub- 

 lished in Gehlen's Journal, a notice of the analysis of a 



