302 Royal Institution : — 



Melsens — that treatment of trichloracetic acid with potassium-amal- 

 gam and water converted it into acetic acid. 



Kolbe was fully sensible of the scope and importance of his disco- 

 very. The following passage occurs in his paper, published in Lie- 

 big's Annalen for 1845: — "From the foregoing observations we 

 deduce the interesting fact that acetic acid, hitherto known only as 

 a product of the oxidation of organic materials, can be built up by 

 almost direct synthesis from its elements. Sulphide of carbon, chlo- 

 ride of carbon, and chlorine are the agents which, along with water, 

 accomplish the transformation of carbon into acetic acid. If we 

 could only transform acetic acid into alcohol, and out of the latter 

 could obtain sugar and starch, then we should be enabled to build 

 up these common vegetable principles, by the so-called artificial 

 method, from their most ultimate elements." Thus it appears that 

 Kolbe looked forward to the building up of organic bodies in gene- 

 ral, and that he was quite alive to the fact that the synthesis of 

 acetic acid completed the synthesis of the derivatives of acetic acid. 



Among these derivatives may be enumerated acetone, the product 

 of the destructive distillation of acetates ; marsh-gas, obtained by 

 distilling an acetate with a caustic alkali ; ethylene, obtained by 

 Bunsen, by heating kakodyle, which itself results by the action of 

 arsenious acid upon an acetate. The electrolysis of acetic acid, 

 which Kolbe accomplished a few years afterwards, yielded methyle 

 and oxide of methyle, which latter, in its turn, could be transformed 

 into any other methylic compound. 



Marsh-gas was moreover prepared by Regnault, by treating C CI 4 

 with nascent hydrogen ; and the common methylic compounds appear 

 to have been produced by Dumas from marsh-gas, the chloride of 

 methyle having been obtained by Dumas by the action of chlorine 

 upon marsh- gas. 



Before 1854, all the foregoing syntheses were fully completed, 

 i. e. there was no step missing between the elements themselves and 

 the most complex compound reached ; but, in addition to these com- 

 plete and definite syntheses, there had also been a good deal of build- 

 ing up of an incomplete or of a less definite character before 1854. 



It was known in a general way, that organic bodies of tolerably 

 simple composition sometimes gave complex products on destructive 

 distillation. Thus alcohol was known to give naphthaline, benzole, 

 and carbonic acid when it was pressed through a red-hot tube. 

 Formiates were also known to yield hydrocarbons when they were 

 subjected to destructive distillation. The precise dates of these 

 different observations I cannot give ; but hand-books of chemistry, 

 published before 1854, contain a statement of the facts. 



A few years after 1820, before W order's celebrated Synthesis of 

 Urea, a very remarkable instance of passage from a simpler to a more 

 complex compound was given by Faraday and Hennel. This exam- 

 ple is placed along with the indefinite syntheses, because it was gene- 

 rally disbelieved in by chemists, and only within the last few years, 

 when it was confirmed by Berthelot, received their general assent. 

 Faraday and Hennel found that olefiant gas was absorbed by sul- 



