250 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



With a view to establishino- tlie atomic weight of sulphur, Erdmann and 

 Marchand also made a series of analyses of mercuric sulphide. These 

 data arc now best available for discussion under mercury. The sulphide 

 was mixed with pure copper and ignited, mercury distilling over and 

 copper sulphide remaining behind. Gold leaf was used to retain traces 

 of mercurial vapor, and the weighings were reduced to vacuum : 



34.3568 grm. HgS gave 29.G207 grm. Hg. 86.215 per cent. Hg. 



24.8278 " 21.40295 " 86.206 



37.2177 " 32.08416 " 86.207 



80.7641 " 69.6372 " 86.223 



Mean, 86.2127. ± .0027 



Hence Hg = 200.520. 



For the percentage of mercury in mercuric chloride we have data by 

 Turner, Millon, Svanberg and Hardin. Turner,^ in addition to some 

 precipitations of mercuric chloride by silver nitrate, gives two experi- 

 ments in which the compound was decomposed by pure stannous chloiide, 

 and the mercury thus set free was collected and weighed. The results 

 were as follows : 



44.782 grains Hg = 15.90 grains CI. 73.798 per cent. 

 73.09 " 25.97 " 73.784 



Mean, 73.791, ± .005 



Hence Hg= 199.665. 



Millon " purified mercuric chloride by solution in ether and sublimation, 

 and then subjected it to distillation with lime. The mercury was col- 

 lected as in Erdmann and Marchand's experiments. Percentages of m.etal 

 as follows: 



73.87 



73.81 



73.83 



73.87 



Mean, 73.845, ± .010 



Hence Hg = 200.224. 



Svanberg," following the general method of Erdmann and Marchand, 

 made three distillations of mercuric chloride with lime, and got the 

 following results : 



'Phil. Trans., 1S33, 531-535. 



-Ann. Chim. Phys. (3), IS, 345. 1846. 



^ Journ. prakt. Chem. , 45, 472. 1848. 



