282 Chronicles of Science. [April, 



before an audience is attended with many difficulties. One of these 

 is the fact, that hydrochloric acid is composed of equal volumes of 

 hydrogen and chlorine. By the electrolysis of hydrochloric acid as 

 usually effected, equal volumes are never obtained ; and the synthesis 

 of equal volumes by the electric spark is never complete. Dr. Hof- 

 mann, however, showed methods of accomplishing both the analysis 

 and synthesis of hydrochloric acid, and satisfactorily demonstrated 

 that two volumes of the constituents produce exactly two volumes of 

 the compound. 



The lecturer next performed an experiment designed to demon- 

 strate the fact, that two volumes of hydrogen and one volume of 

 oxygen, combine to produce two volumes of aqueous vapour. To 

 show this, the tube containing the mixed gases is enclosed in another 

 tube, through which a current of the vapour of boiling amylic alcohol 

 is maintained. The temperature of the mixed gases is thus kept at 

 about 130° 0. On passing the electric spark explosion ensues as usual, 

 but the water formed is necessarily retained in a state of vapour, and 

 on opening the tube under mercury it is seen that the compound 

 resulting from the explosion only occupies two-thirds of the bulk of 

 its constituents.* 



The constitution of ammonia by volume was next illustrated, as 

 usual, by means of the induction spark. It was shown that by the 

 passage of the sparks the gas was resolved into constituents which 

 occupy twice the volume of the compound. But the most striking 

 experiment exhibited was that which showed the exact bulk of the 

 nitrogen present in ammonia. A long tube marked into three divi- 

 sions, by India-rubber rings, was filled with chlorine, and to the open 

 end was adapted a small globe containing strong ammonia. On allow- 

 ing a few drops of the liquid to enter the tube, a flash of light was 

 observed ; more ammonia was then admitted, and the tube was warmed 

 to complete the decomposition. A little dilute sulphuric acid was 

 then introduced to remove excess of ammonia ; and now the tube 

 being opened in communication with the same liquid, it became filled 

 to the extent of two-thirds, leaving one-third full of pure nitrogen. 

 Since it had been shown in a previous experiment that chlorine always 

 unites with a volume of hydrogen equal to its own, the last experi- 

 ment proved that in ammonia three volumes of hydrogen are united 

 with one volume of nitrogen. 



The only typical compound remaining, the volume composition of 

 which requires demonstration, is marsh gas ; at present, however, we 

 have no means of experimentally illustrating the composition of this 

 body. 



Another paper, of much interest, was by Mr. Broughton, describing 

 a new reaction for the production of anhydrides and ethers. The 

 ready decomposition of sulphide of carbon, at a high temperature by 

 metallic oxides, and even by water, with, in the latter case, the produc- 

 tion of carbonic anhydride, led the author to think that by the action 

 of sulphide of carbon on organic metallic salts, a sulphide of the 



* It is right to say that this beautiful experiment, which was not completely 

 successful before the Chemical Society, Dr. Hofmann repeated with most perfect 

 success in one of his recent lectures at the Royal Institution. 



