410 



NA TURE 



[August 23, 1894 



pointed out that the atoms of gases can change 'he.r tnode of 

 Combination independently of water, ..,- m the decomposition 

 of potassium chlorate, and in the conjbust.on of carbon d.- 

 sulphide. He suggested that the residual glow is due to the 

 reformation of the original molecules. :„j„Miv^ 



Prof Fitzcerald drew attention to the high specific inductive 

 capacity of water, and con.ended that Prof. Thomson s ex- 

 piration of his results meant simply that m a large molecule 

 the atoms can change places. „„,., 



The President understood Prof. Thomson to hold that water 

 was present in actual drops, and queried whether that could be 

 so in the explosion of carbon monoxide, where a very higb 

 temperature is reached. u . • > 



Prof. Thomson, in his reply, seemed of opinion that minute 

 drops might be present even in the case mentioned by 1 rot. 

 Dixon. In conclusion he urged the desirability of the Prepara- 

 tion of pure compounds in the large laboratories of the 

 country, which might be sent to the physicist for investigation. 

 Prof Hartley then described some new methods of spectrum 

 analysis and some Bessemer flame spectra. He has found that 

 if a mixture containing alkalies and alkaline earths be fused 

 with borax or silica, the alkalies are f^rst volatilised and give 

 their characleristic spectra very clearly ff obtaining spectra 

 at hi-h te-uperatures it has been found useful to heat the sub- 

 stance in the oxy-hydrogen flame on a rod of kainite, P-P^-^lay. 

 or dried alumina. The elements can be classified according to 

 the type of spectrum given under these conditions. On vapour- 

 i.ine alloys, those constituents which, when free, give band 

 spectra, are found to produce line spectra, 'A\ ^'';;"' '".jl" 

 alloy of copper and silver. This is thought to be due to the 

 difference between the vapour pressure of the element when 

 alloyed, and when in the free state. . .• j -.u 



The spectrum of the Bessemer flame has been studied with 

 special reference to the bands produced by manganese. 



Mr I W. Thomas read a paper on the chemistry of coal 

 fonnaliin, in which he endeavours to trace the connection 

 between the properties of a coal and the character of the vege- 

 tation from which it probably originated. 



On -Monday a large audience assembled to hear the an- 

 nouncement by Lord Rayleigh and Prof. Ramsay of the 

 existence of a new gas in the atmosphere. It appears that 

 certain experiments of Cavendish pointed to the presence, in 

 air, of some substance other than the gases ""h "'hich we are 

 familiar. Attention was recalled to this substance by the fact that 

 the density of nitrogen obtained fom atmospheric air differs by 

 about 1 per cent, from the density of nitrogen obtained from 

 other sources. It was found that if air (with excess of oxygen) 

 be subjected to electric sparks, the resulting nitrous fumes 

 absorbed by potash, and the excess of oxygen by alkaline 

 pyrogallate, there remains a residue which is neither oxygen 

 nor nitrogen, as can be seen from its spectrum. The same gas 

 can be isolated by exposing nitrogen obtained f^-" /"'r ° '!?= 

 action of magnesium. As the mDgne.ium gradual y absorbs 

 the nitrogen,''the density of the residual gas g'adually nses " 

 nearly 20 The newly discovered substance constitutes ne.irly 

 I per cent, of the atmosphere, and gives a spectrum Willi a 

 single blue line much moie intense than a corresponding blue 

 line in the nitrogen spectrum. ,.,i„;„„ „„ 



Sir H. K. Roscoe, in proposing a vote of congratulation on 

 the discovery, sp ,ke of the special interest which attached to it 

 as being the outcome of a purely physical observation. 



Prof Emerson Reynolds noted the place which the new sub- 

 stance, if it proved to be an clement, would occupy in Men- 

 delcefj table among the platinum metals. 



Prof Roberts- Austen suggested that this g.as might be the one 

 which is frequently found as a residue among the gases extracted 



"rhc "resident, in putting the vote of congratulation to the 

 meeting, drew attention to an observation made by Prof. IJewar, 

 that while a mixture of pure liquefied oxygen and nitrogen 

 forms a clear liquid, air in a similar state shows a '•"'"dity 

 The President suggested that this turbidity might be due to the 



"^Th'i*^'uction U discu.scd by Prof. Dcwar in a letter to the 

 Timtt for August 1 6, in which he states that the substance 

 causing turbidity does not amount to 1 per cent, of the whole 



"^The next communication was by Prof. McLcod, on Schuler's 

 jellow modification of arsenic. This is produced as a yellow 

 ioblimatc when pure arsenic is heated in vacuo. The substance 

 rapidly changes to the black modification. 



Some very interesting experiments on the electrolysis of glass 

 were described by Prof. Roberts Austen. In conjunction with 

 Mr Stansfield he has found that if a bulb of soda-glass be filled 

 with sodium amalgam and immersed in a vessel of mercury 

 heated in a sand-bath to rather over 200°, on connecting the 

 sodium amalgam and the mercury respectively with the terminals 

 of a battery, sodium will pass from the amalgam through the 

 glass into the mercury. At the end of the experiment the glass 

 is unchanged. If lithium amalgam be substituted for the 

 sodium amalgam, however, a certain percentage of lithium is 

 found in the gl.iss at the end of the experiment, sodium from 

 the glass is driven into the mercury, and the glass is altered in 

 appearance and frangibility. With potassmm amalgam and 

 soda-glass no change takes place. These phenomena are 

 believed by Prof. Roberts-Austen to depend on the relative 

 atomic weights and consequent atomic volumes of the elements 

 concerned. Lithium, having a smaller atomic volume than 

 sodium, is able to follow in the galleries left by the atoms of 

 the latter metal ; potassium, on the other hand, having an 

 atomic volume greater than sodium, cannot force a passage. 

 From the results he has obtained, using other amalgams, such 

 as those of gold and copper and different kinds of glass, I rof. 

 Roberts-Austen hopes to throw light on the formation of 

 mineral veins in rocks which apparently have not undergone 



"*Mr ' T W Rodger gave an account of the experiments which 

 have been conducted by Prof. Thorpe and himself on the 

 relations between the viscosity of liquids and their chemical 

 nature. The method adopted allowed a rapid succession of 

 experiments to be made on the same liquid a d.fte.entem- 

 peratures. In the case of the fatty acids and alcohols examined, 

 evidence has been found of the existence of molecular aggrc- 



^*Dr' T H. Gladstone described some experiments on the rate 

 of progress of chemical change. The chief reaction investigated 

 was that which takes place when platinum chloride and 

 potassium iodide are mixed, resulung in the formation o the 

 dark coloured iodide. This change begins r.ipdly, wi no 

 period of ineriness or "reluctance." Its completion is much 

 retarded, however, by the presence of potassium chloride A 

 change which does require time to att.i.n a maximum rae is 

 that which takes place when cuprous oxide is immersed in a 

 solution of silver nitrate, the silver which is produced making 

 its appearance only after some time. 



A similar change to the latter was described by M. Paul 

 Sabatier, in which litharge added to silver nitrate solution IS con- 



verted into the pucecoloured oxide of lead, with simultaneous 



•"'rplpeVJafreadbyMr. Vernon IL.rcourt, in the name of 

 the la^t^Mr Percy B. Lewis, on a new and very delicate method 

 for determining the freezing points of very dilute solulions 



Dr M. Wildermann gave an account of_ experiments he had 

 made with Mr. Lewis's apparatus, and said that they fully con- 

 Tniedthe predictions of the Vant llofl Arrhemus ihe.ry. 



Mr W W. Randall described his apparatus for "leasur ne 

 the colour-tint of dilute solutions. His experiments, instuut<^ 

 n order to determine whether dissociation takes place in dilute 

 solutions, are of a qu-ilitative char.acler. At their commence- 

 ment he was not aware of the careful spec.romelnc work of Dr. 



''"Mri;mr>'S«ad'a paper on the distinction between 

 compounds and ho'mogencou^s mixtures, a P-''^^ °^ J^;'''^ 

 recently appeared in a letter to Naiurk. He showed that 

 until alely there was no satisfactory experimental c"lerion for 

 d"st inguishing easily between true compoun<ls and such mixtures, 

 bu the ecem work of K.aoull showed that the ('cc'-nR P" "' of 

 a pure compoun,! was always lowered, and its boiling point 



"pfof '7 A"\vank?;n"paper on new evidence as to the a.on^ 

 ^h ^rbon w s ;;^cJive.|^w.h ..crest, ;Hough riot w. 



KTslaTpeUo'i^'um 'h'c' a uhorh'^nUatned hyr.rocarbons of 

 constant Ging point, whose vapour densities point to their all 

 containinc carbon atoms of the weight f). ,,„,„= for 



lo combine with all the carbonic .icid present ^-c^^^.^^ of 



Mr A. P. Laurie contributed a paper on .''^ "'"" ° „ ' 



very bUute Solutions of Chlorine and Iodine. 1 he interest 



NO. 1295. VOL. 50] 



