Chemistry and Physics. 53 
tion to the result of Foucault, 298,000 kilometers, and also corres- 
ponds very closely to the value obtained from the solar parallax, 
which has recently been calculated by Leverrier from observations 
upon Mars and Venus to be 8°86. Cornu believes that with sta- 
tions separated from 20 to 30 kilometers, it would be possible by 
this method to obtain a value accurate to within a thousandth.— 
C. R., \xxvi, 388, Feb., 1873. ; oem 
. On the Activity of Chlorine in the dark,—Metsens has 
observed that carbon in the form of coke, purified by repeated 
Sead 
nearly its own weight of this gas. If now a current of hydrogen, 
upon potassium dichromate, the yield is unsatisfactory, the pro- 
duct is impure, and the process is tedious. DuviLtIER proposes 
to boil together for ten minutes 100 parts of barium chromate, 100 
parts of water, and 140 parts of nitric acid of 40° B. To the red 
liquid, 200 parts more of water are added, and the whole is boiled 
ten minutes longer. On cooling, barium nitrate is deposited in 
C,H yu4,0Na+CO= | Gy SNE 
Brrruetor has re-investigated the action under these circum- - 
stances, trace of moisture, barium alcoholate 
water, and iso- 
meric with propionic acid, a trace of which 1s simultaneously 
formed.— Bull. Soc. Ch., IL, xi 
: - Soc. Ch. xix, 160, Feb., 1873. G. F. B. 
‘ On the JSormation and decomposition of Ketones.—The split- 
sion with potassium h te, of benzophenonparadi- 
