30 ATOMIC AVEIGIIT DETERMINATIONS. 



G. FowNES: 12.12 (0 = 16). 



Determined by three analyses of naphthaline with cupric 

 oxide, the usual precautions being observed. The value is 

 the mean ; extreme difference, 0.14. The naphthaline was 

 purified b}^ slow sublimation in a florence tlask, and was 

 brilliantly white. Fownes does not regard his results as 

 conclusive as to the exact value. {Phil. 31ag., (3,) i5, 1839, 

 62.) 



E. MiTSCHERLiCH : 12.016 (O = 16) ; 75.1 (0 = 100). 



Experiments made on the analysis of naphthaline by the 

 ordinary method of organic analysis gave never more than 

 75.2, and those wdiich seemed most accurate very nearly 75. 

 {Mitscherlich' s Lehrbuch der Chemie, 4th ed., 1, 1844, 595.) 



Dumas and Stas : 1:? (0 = 16); 75 (0 = 100). 



Determined by fourteen experiments on the combustion 

 of carbon in oxygen, the resulting carbon di-oxide being 

 weighed. In five cases natural graphite was employed, and 

 in four graphite from charcoal pig-iron. Both were puri- 

 fied by treatment with acid and heating in chlorine. The 

 necessary oxygen was developed in the combustion-tube 

 from potassic chlorate and cupric oxide. In five experi- 

 ments diamond was employed, and the oxygen was furnished 

 from a gasometer. The oxygen was displaced by air, espe- 

 cially purified from carbon di-oxide by milk of lime. The 

 products of combustion were collected in tubes filled with 

 pumice stone moistened with sulphuric acid, Liebig potash- 

 bulbs and tubes filled with dry potash. The mean of the 

 experiments on graphite gave = 74.982; those on dia- 

 mond gave 75.005 ; the extreme difference was 0.238. The 

 observers point out that the result would not be affected by 

 reduction to vacuum. [Annal. de Chimie et de Phi/sique, (3,) 

 i, 184], 5.) 



Liebig thinks that potash must have been volatilized, and 

 says that there is no assurance that the oxygen was com- 

 pletely expelled by air. He also points out that the analyses 

 of camphor and benzoic acid, accompanying the investiga- 

 tion, show an excess of carbon for = 75. {Licbig's 

 Anrial, 38, 1841, 195.) 



Erdmann and Marcuand : 12.000 (0 = 16) ; 75.054 

 (0 = 100). 



Erdmann and Marchand repeated Dumas' and Stas' ex- 

 periments. Five experiments on diamond gave = 75.028 ; 



