254 



SCIENCE. 



[Vol. IV., No. 84. 



fusion of gold, silver, and platinum in lead. The 

 rate of diffusion in these cases, and notably in the 

 case of gold, seems to be enormously high compared 

 with the rate of diffusion in liquids. 



Mr. W. J. Millar read a paper on iron and other 

 metals in a liquid and solid state, which started a 

 lively and entertaining discussion of the question of 

 the expansion of iron on solidification. Mr. Millar 

 contended that iron did not expand on solidification; 

 while Sir William Thomson, and other members of 

 the section, protested that Mr. Millar's own experi- 

 ments proved conclusively that it did. 



The matter of the velocity of light of different col- 

 ors was considered by Professor Michelson, and also by 

 Professor George Forbes. Mr. Michelson explained, 

 somewhat in detail, his method of determining the 

 velocity of light, and gave the results of an investi- 

 gation of the velocity of red and blue through a col- 

 umn of carbon bisulphide about ten feet long. The 

 velocity of the mean ray through this medium had 

 been found to be about 1.75 times its value in air, 

 which was somewhat higher than theory would indi- 

 cate ; but the difference was doubtless attributable to 

 errors in experiment. A measurable difference be- 

 tween the velocity of the red and that of the blue 

 ray had been observed, agreeing very closely with 

 that indicated by theory. Professor Forbes' s paper 

 was a discussion of the observations by means of 

 which he, in junction with Mr. Young, had shown, 

 apparently, that there was a measurable difference be- 

 tween the velocities of red and blue light in air. The 

 paper was discussed by Sir William Thomson, Lord 

 Rayleigh, Professor Newcomb, Professor Michelson, 

 and several others ; and the general opinion was quite 

 decidedly against the view that such difference really 

 existed. 



On the last day of the session, the section was di- 

 vided ; and a number of papers on pure mathematics 

 occupied the attention of a sub-section. No report of 

 these papers can be made, as the Science reporter 

 found it impossible to organize a sub-section to follow 

 the mathematicians. 



PROCEEDINGS OF THE SECTION OF 

 CHEMICAL SCIENCE. 



The session opened at noon, Aug. 28, with the 

 president, Sir Henry E. Roscoe, in the chair. Dr. 

 Perkins, the retiring president, sat on his right hand; 

 and Drs. Wolcott Gibbs, Gladstone, and Frankland, 

 on his left. The room was filled to overflowing; and 

 the address was listened to with marked attention 

 and interest, and the comments upon it were uni- 

 form in their commendation. This is rather surpris- 

 ing when we recall the present state of feeling in 

 England which the efforts to found a superior insti- 

 tution for technical instruction have aroused, but 

 his views on chemical education are in conformity 

 with those generally entertained in the United States. 

 It will be seen by the papers presented at this session, 

 that the particular phases of the recent advances in 

 chemistry of which the president treated occupy 



at present the attention of many of the English 

 chemists. 



The first paper read was by Dr. Wolcott Gibbs, at 

 the request of the section, and was upon the complex 

 inorganic acids. It consisted of a resume of the 

 magnificent work which he has done in the field 

 which he has discovered and explored. 



It is impossible in the brief space at our command 

 to do justice to this superb research ; which is destined 

 to revolutionize many of our chemical conceptions, 

 and in which has been shown the cumulative power 

 of the molybdenum and tungsten oxides, the exist- 

 ence of dominant and subdominant groups, and of 

 different kinds of basicity prevailing within the same 

 molecule, and of the production of isomerism by the 

 orientation of the atoms. 



Mr. H. B. Dixon exhibited tables in which Bun- 

 sen's, Horstmann's, and his own results on the effect 

 of mass on the incomplete combustion of mixtures of 

 carbon monoxide, hydrogen, and oxygen were com- 

 pared ; and the discrepancies were found to be due to 

 differences in the temperature and pressure under 

 which the experiments were conducted. Above four 

 hundred millimetres, the pressure did not affect the 

 results; and at temperatures between 60° and 140° 

 constant results were also obtained. It is believed, 

 that when the mixtures were exploded below 60°, the 

 reaction was interfered with by the condensation of 

 water on the sides of the tube. Further, it was found 

 that mixtures of carbon monoxide and oxygen, in 

 equivalent proportions, could not be exploded unless 

 there were aqueous vapor, or some body containing 

 hydrogen, present. With traces of hydrogen, hydro- 

 chloric acid, hydrogen sulphide, or a hydrocarbon 

 present, the mixture could be exploded. It is sup- 

 posed that the steam is reduced by the carbon mon- 

 oxide, and that the liberated hydrogen burns, and 

 re-forms steam, which again acts on more carbon 

 monoxide. By a series of alternate reductions, a 

 few molecules of steam serve to carry oxygen to the 

 carbon monoxide just as the oxide of nitrogen acts 

 in the sulphuric-acid chamber. By putting a dry 

 mixture of carbon disulphide and oxygen into a dry 

 mixture of carbon monoxide and oxygen, the first 

 could be inflamed, then by introducing a little water 

 the carbon monoxide and oxygen could be exploded. 



Professors Liveing and Dewar read a paper on the 

 spectral lines of the metals developed by exploding 

 gases. Berthelot has recently investigated, by means 

 of the chronograph, the rate of propagation of the 

 explosion of mixtures of oxygen with hydrogen and 

 other gases ; and has found, that, with a mixture of 

 hydrogen and oxygen in the proportion to form 

 water, the explosion progresses along a tube at the 

 rate of 2,841 metres per second, a number which is 

 not far from the velocity of mean square for hydrogen 

 particles, on the dynamic theory of gases, at a tem- 

 perature of 2,000°. 



This velocity, though far short of the velocity 

 of light, bears a ratio to it which cannot be called 

 insensible. It is, in fact, about ttttjWo part of it. 

 Hence, if the explosion were advancing towards the 

 eye, the waves of light would proceed from a series of 



