116 THE ATOMIC WEIGHTS. 



With a view to establishing the atomic weight of sulphur 

 Erdmann and Marchand also made a series of analyses of 

 pure mercuric sulphide. These data are 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 29.6207 grm. Hg. 86.215 percent. Hg. 



24.8278 " 21.40295 ••' 86.206 " 



37.2177 " 32.08416 " 86.207 " 



80.7641 " 69.6372 " 86.223 " 



Mean, 86.2127, ± .0027 



For the percentage of mercury in mercuric chloride we 

 have data by Turner, Millon, and Svanberg. Turner,* in 

 addition to some precipitations of mercuric chloride l)v silver 

 nitrate, gives two experiments in which the compound was 

 decomposed by pure stannous chloride, 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 



ISIillonf purified mercuric chloride by solution in ether 

 and sublimation, and then subjected it to distillation with 

 lime. The mercury was collected as in Erdmann and Mar- 

 chand's experiments. Percentages of metal as follows : 



73-87 



73-81 



73-83 

 73-87 



Mean, 73.845, dz -Oio 



Svanberg,! following the general method of Erdmann 



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



f Ann. Chim. Phys., (3,) 18, 345 1846. 



J Joiirn. flir Prakt. Chem., 45, 472. 1848. 



