Chemical Notices : — On the Reduction of Carbonic Acid. 299 



in the ratio of the moon's density to that of the earth/ that is, 

 to about frds of the values already given. 



The same method of course applies equally to the sun ; and 

 whether his magnetism be regarded as exceeding that of the earth 

 in proportion to his mass or to his bulk, his maximum influence 

 will be even less than that of the moon ; for he never attains an 

 apparent size as great as the maximum of the moon, and his 

 density is only about half that of the moon. 



XXXIX. Chemical Notices from Foreign Journals. 

 By E. Atkinson, Ph.D., F.C.S. 



[Continued from p. 143.] 



FROM the readiness with which, in the vegetable kingdom, the 

 oxygen in carbonic acid is replaced by hydrogen, it was highly 

 probable that carbonic acid could similarly be reduced artificially, 

 and that the first product of substitution (formic acid) could be 

 prepared from carbonic acid. Led by these considerations, 

 Kolbe and Schmitt* undertook an investigation on the direct 

 conversion of carbonic acid into formic acid, and their first expe- 

 riments have been successful. The change succeeds so easily and 

 in such a simple manner as to make it surprising that it has not 

 been previously observed. When potassium was spread out in a 

 thin layer on a flat dish, and this was placed under a bell-jar 

 standing over milk-warm water, and kept continually filled with 

 carbonic acid, the potassium was found in twenty-four hours to 

 be converted into a mixture of bicarbonate and of formiate of 

 potash. The reaction may be thus written : — 



2K + 2C 2 4 + 2HO = KO,C 2 H0 3 + hq|c 2 4 . 



The above mixture was supersaturated in the cold with sulphuric 

 acid, the acid liquor poured off from the bisulphate of potash 

 distilled, and the distillate neutralized with carbonate of lead. 

 On evaporating the hot filtered solution, chemically pure for- 

 miate of lead was obtained. 



Sodium exposed for twenty-four hours to the action of car- 

 bonic acid and aqueous vapour, also gives rise to the formation 

 of formic acid, but in smaller quantity than potassium. 



Schischkoff, in continuing his researches on nitroform t, has 

 obtained results of which he communicates a preliminary noticef . 



* Licbig's Annalen, August 1861. 



t Phil. Mag. vol. xv. p. 302. 



J Liebig's Annalen, August 1861. 



X2 



