1865.] Chemistry. 279 



the solubility is not affected by these agents. The authors seem to 

 regard this power of carbon, and bodies rich in carbon, to alter the 

 physical and chemical properties of sulphur, as to some extent com- 

 parable to the effect of carbon in the conversion of iron into steel. 



One practical resirit of these investigations has been to show the 

 possibility of making large plates of sulphur for electrical machines 

 which will be unaffected by moisture and atmospheric influences. 



The mention of bisulphide of carbon recalls to our mind that Mr. 

 Lewis Thompson has lately made public* a simple method of re- 

 moving this pernicious ingredient from gas. He takes advantage of 

 the fact that the vapour of bisulphide of carbon, and the vapour of 

 water cannot exist together at a high temperature without undergoing 

 a double decomposition resulting in the formation of sulphuretted 

 hydrogen and carbonic acid. He therefore proposes to mix the gas as 

 soon as it leaves the hydraulic main with a certain amount of steam, 

 and to send the mixture through tubes heated to redness, in which 

 the decomposition will take place. The resulting compounds, as 

 probably all our readers know, are common ingredients in raw gas, 

 and will be removed by the ordinary methods of purification. How 

 this process will answer on the scale of manufacture common in our 

 large gas-works we cannot say ; but seeing the objectionable effects 

 which are produced by the sulphurous acid generated in the com- 

 bustion of sulphide of carbon, and probably other sulphuretted com- 

 pounds in gas, the process deserves a serious trial. 



Deville continues his valuable researches on the phenomena of 

 dissociation, and has now invented an ingenious apparatus by which 

 the partial decomposition of bodies below the temperature of com- 

 plete decomposition can be satisfactorily demonstrated. This appa- 

 ratus! consists of a porcelain tube, which carries within it a copper 

 tube of smaller diameter. The tube being disposed in a convenient 

 furnace, the gas to be experimented upon is passed through the 

 porcelain tube, and at the same time a current of cold water is sent 

 through the copper tube. The diminished temperature in the neigh- 

 bourhood of the inner tube prevents the recombination of the separated 

 components, and by certain arrangements the facts of the dissociation 

 are clearly shown. Thus, in the case of carbonic oxide free carbon is 

 deposited on the surface of the inner tube, while carbonic acid is 

 found in the escaping gas. Sulphurous acid is dissociated into sul- 

 phur and oxygen, which latter unites with the excess of sulphurous 

 acid to form sulphuric acid. In order to show this, Deville coats the 

 surface of the copper tube with silver, which becomes blackened by 

 the sulphur, while the sulphuric acid may be washed from the sur- 

 face, and detected by means of baryta. The dissociation of hydro- 

 chloric acid is shown as clearly by amalgamating the silvered surface 

 of the tube. By this means chlorine is fixed as chloride of silver and 

 mercury, while free hydrogen is found in the gas which escapes. 



The author does not appear to have experimented in the above 

 way with carbonic acid and ammonia; but he states the results 



* ' Newton's Journal of Arts,' Feb. 18G5. 

 t ' Comptes Rendus,' Nov. 28, 1864. 



