MERCURY. 1 15 



to represent the percentage composition of both the chlo- 

 rides of mercury ; but these results are neither reliable nor 

 in proper shape to be used. 



First in order we may consider the percentage composi- 

 tion of mercuric oxide, as established b}^ Turner and by 

 Erdmann and Marchand. In both investigations the oxide 

 was decomposed by heat, and the mercury was accurately 

 weighed. Gold leaf served to collect the last traces of mer- 

 curial vapor. 



Turner gives four estimations.* Two represent oxide ob- 

 tained by the ignition of the nitrate, and two are from com- 

 mercial oxide. In the first two the o:side still contained 

 traces of nitrate, but hardly in weighable proportions. A 

 comparison of the figures from this source with the others 

 is sufficiently conclusive on this point. The third column 

 represents the percentage of mercury in HgO : 



144-S05 grains Hg 

 125.980 

 173.561 

 114.294 " 



Mean, 92.614, ±: .0050 



In the experiments of Erdmann and Marchand f every 

 precaution was taken to ensure accuracy. Their weighings, 

 reduced to a vacuum standard, give the subjoined percent- 

 ages: 



*Phil. Trans., 1833,531-535. " 



f Journ. fiir Prakt. Chcm., ^I, 395- 1844. 



