RECENT PROGRESS IN PHYSICS. 391 



stratum of oil collected upon the fluid had reached a height of several 

 lines, and the greatest part of the valerianate of potassa had been 

 clianged into carbonate and bi-carbonate of potassa^ the latter of 

 which usually partly crystalized at the end of the process. In order 

 to ascertain at which pole each of these products appeared, Kolbe 

 placed the platinum plate in a porous clay cell, which was closed air- 

 tight at the top and i)rovided with a tube for conducting oif the gas 

 evolved. This cell, filled with valerianate of potassa, was set in a 

 glass vessel also containing a solution of this salt, and in which the 

 copper cylinder serving as the negative pole was placed. AVith this 

 arrangement it was found that of the above mentioned products of 

 decomposition, besides free potassa, only hydrogen occurred at the 

 negative pole, while all the others, the essential oil, the carbonic acid, 

 and the odorous gas, accompanied by free acid, (the arrangement of 

 the apparatus prevented tlie formation of carbonate of potassa^) ap- 

 peared at the positive pole. 



Kolbe then proceeded to an accurate examination of the individual 

 products of decomposition. At first he investigated the oily flnid. 

 It soon appeared that the crude oil was not a single substance. By a 

 process which cannot here be described in detail, lie found the crude 

 oil to be a mixture of two different substances. After purification, 

 the volume was reduced to about one-half, and the fluid thus obtained 

 was limpid and colorless, of a very agreeable ether-like odor, and of 

 a flat and afterwards burning taste. It is soluble in alcohol and ether, 

 but not in water, boils at 108°, is very inflammable, and of remarkably 

 low specific gravity, viz: 0.694. 



The chemical formula of this body, which Kolbe calls valyl, is Cg 

 Hg, i. e., it consists of 8 equivalents of carbon, and 9 equivalents of 

 hydrogen. 



The crude oil is valyl mixed with Cg Hg -|- (Cg Hg) Cg O3, viz : 

 with valerianate of oxide of valyl. The odorous gas which escapes 

 with the carbonic acid, is also a hydro-carbon, viz : Cg H3, and there- 

 fore of the same composition as olefiant gas, to which it is also analo- 

 gous in its relation to chlorine^ but its specific gravity is twice as 

 great. 



The whole course of these decompositions is now easily compre- 

 hended. By the oxygen evolved in consequence of the electrolysis at 

 the positive pole, the valerianic acid (C^ H^) Cj O3 is oxydized and 

 broken up into valyl C3 Hy and carbonic acid, or rather the valyl itself 

 undergoes again a partial oxidation, and forms oxide of valyl Cy H,, 0, 

 which combines with valerianic acid and produces with the remaining 

 valyl the crude oil. Besides this, a secondary oxidation of the valyl 

 occurs by reason of the nascent oxygen abstracting from it 1 equiv. of 

 hydrogen to form water, wheieby the substance C^ Jl^ homologous 

 with olefiant gas is produced, which, with the carbonic acid, escapes at 

 the -}- pole. 



Acetic acid undergoes similar decompositions by the influence of the 

 galvanic current. Acetic acid being too poor a conductor, Kolbe 

 also used its potash salt for his experiments. Acetic acid (G, H3) 

 C2 O3, like valeric acid is oxidized at the -\- pole, and thereby sepa- 

 rated into methyl Cj H3 and carbonic acid C2 0^ or rather 20 O2, 



