114 ATOMIC WEIGHT DETERMINATIONS. 



J. J. Berzelius : 32.19 (O = 16) 201.165 (0 = 100). 



A known weight of lead was dissolved in pure nitric acid, 

 precipitated with sulphuric acid and evaporated. The mean 

 result of four experiments was that 100 Pb = 146.44 sul- 

 phate. The variation was only in the fifth figure. If lead 

 = 1294.498 the value follows. [If this relation is recalcula- 

 ted with Stas's atomic weight of lead, S = 32.096.] (Poggend. 

 Ann. 8, 1826, 16.) 



E. Turner: 32.17 (0 = 16). 



Determined from syntheses of plumbic and baric sul- 

 phates. The former gave 16.083, the latter, 16.087. Ba = 

 68.7, Pb = 103.6. The numbers are for vacuum. Vide 

 Barium and Lead. {Phd. Trans., 123, 1833, 539.) 



T. Thomson : ,^^ (O = 16) ; 200 (O = 100). 



This chemist found the specific gravity of sulphurous 

 acid in mean of two experiments, 2.22216, almost exactly 

 double 1.1111 which he takes (on utterly untenable grounds) 

 for the specific gravity of oxygen. [Erdmann^ s Journ. fiir 

 Prak. Chem., 8, 1836, 370; Records of General Science by R. 

 D. Thomson, 1836, 179.) 



Erdmann and iMarchand : 32.004 (0 = 16) ; 200.026 

 (O = 100). 



Determined by four experiments on the decomposition of 

 mercuric sulphide by copper, in a current of carbon di- 

 oxide, the mercury being caught in a cold receiver. The 

 mean composition was found to be for vacuum 86.211 mer- 

 cury and 13.789 sulphur, extreme difiference, 0.017 Hg. If 

 Hg = 1250.6, the value follows. In purifying the sulphide 

 it was first heated to drive oif excess of sulphur and then 

 sublimed three times, the first and last portions of the sub- 

 limate being rejected. {JErdmann's Journ. fiir Prak. Chem., 

 31, 1844, 396.) 



J. J. Berzelius : 32.12 (0 = 16) ; 200.75 (O = 100). 



Berzelius' former value, 201.165, is changed by the new 

 value for lead, 1294.645 to 200.8017. Three nevv experi- 

 ments were made by gently heating argentic chloride in a 

 current of hydrogen disulphide. The ^mean of three ex- 

 periments gives S = 200.706 ; extreme difl:erence 0.11. CI 

 = 443.38, Ag = 1349.66. {Berzelius' Jahresbericht, 25, 1845, 

 37, and Lehrbuch, 3, 1185.) 



