CHEMICAL SCIENCE. 181 



fiven. The composition of this is also a matter of doubt, but it is a 

 ody of a somewhat similar composition to silicon, and in the presence 

 of alkalies it behaves in the same way with some metallic salts. The 

 mode of formation of leukon from silicon, under the influence of light, 

 is also obscure ; the most probable theory is that four atoms of water 

 are decomposed, four of oxygen and one of hydrogen uniting to the sil- 

 icon, and the other three of hydrogen being set free." 



MANUFACTURE OF ALCOHOL BY ILLUMINATING GAS. 



The French correspondent of Silliman's Journal thus describes a 

 process of manufacturing alcohol at a very low cost from common 

 illuminating gas which has been devised in France, and which has of 

 late attracted attention ; a quantity of alcohol so prepared being one of 

 the principal curiosities at the last London Exhibition. To carry out 

 this invention, the patent for which has been issued to a French chem- 

 ist, by the name of Cotelle, a company has been organized at St. Quen- 

 tion, France. " The patent," says the correspondent of the Journal, 

 " is founded upon the experiment by means of which Berthelot, in 1855, 

 accomplished the synthesis of alcohol, by causing the absorption of ole- 

 fiant gas, C 4 H 4 , by sulphuric acid, thus converting it into sulpho-vinic 

 acid, a compound readily turned into alcohol by processes long since 

 known. This experiment, made known by Hennell, thirty years ago, 

 has now been repeated with C 4 H 4 prepared from alcohol. Mr. Cotelle 

 employs mostly illuminating gas, which, as we know, contains from 

 four to twelve per cent, of C 4 H 4 . Separating this, by means of sul- 

 phuric acid, there remains a gaseous mixture, composed of C 2 H 4 , CO, 

 H, &c.j very suitable for burning, so that this first material ought to 

 cost very little, especially if the manufacture be undertaken at the 

 mines, so as to take advantage of the gas which issues from the coke 

 furnaces. 



" To produce one hectolitre of alcohol of ninety per cent., Mr. Cotelle 

 uses not more than forty cubic metres of C 4 H 4 , which corresponds to 

 about two tons of the northern coal used at St. Quentin. But the dif- 

 ficulty is not solely in the production of C 4 FF ; there is also needed a 

 large amount of concentrated sulphuric acid, (ten parts of HO SO 3 to 

 one of alcohol). This, used at 66 of Beaume's areometer, remains, af- 

 ter the completion of the work, at from 20 to 25. It is necessary, 

 then, either to concentrate it again for a new process, or to utilize it 

 in its diluted state ; from this, we see the necessity for either concen- 

 trating apparatus or leaden chambers ; for a hectolitre of alcohol re- 

 quires for its production 1500 kilometres of sulphuric acid at 66. Thus 

 we perceive a series of difficulties which are not yet overcome, but 

 which are vanishing, day by day. Still, Cotelle's process is interesting, 

 and we w r ill give it in a few words. Starting with the purification of 

 gas, we free it from sulphydric acid and ammonia, then desiccate it by 

 passing it over HO SO 3 . Drawn along by suction like that of a pump, 

 the dry gas is directed to a column of glass or sandstone furnished with 

 trays or diaphragms pierced with small holes, from which descends HO 

 SO 3 in a finely divided state, to meet and dissolve the C 4 H 4 . This so- 

 lution takes place slowly, so that the apparatus needs as many as forty 

 trays to distribute enough sulphuric acid to absorb the gas and be satu- 

 rated with it. . The sulpho-vinic acid thus obtained is next treated with 



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