August 23, 1894] 



NATURE 



409 



Thomson first proved by experiment that a magnet acts on the 

 cathode rays through the whole of their course, and does not 

 merely affect the place on the cathode at which they have their 

 origin. He then proceeded to investigate the velocity with 

 ■which the cathode rays travel, for it seemed that a know- 

 ledge of this velocity would enable us to discriminate 

 between two views as to their nature. If they are ethereal 

 waves, we should expect them to have a velocity comparable with 

 that of light ; if they are caused by molecular streams, their 

 velocity should be that of the molecules, which we should expect 

 to be very much smaller than that of light. The value found for 

 the velocity of the cathode rays was l'9>; lo" cm./sec, which is 

 small compared with the velocity of the main discharge from the 

 + to the - electrode. It is much greater than the velocity 

 of mean square of the molecules ; it agrees very nearly with the 

 velocity which a negatively electrified atom of hydrogen would 

 acquire under the influence of the potential fall which occurs at 

 the cathode. 



On Wednesday, JI. Cornu exhibited some brilliant optical 

 experiments illustrating Babinet's principle. Prof. W. Forster 

 described the displacements of the rotational axis of the earth. 

 His results had been deduced by investigating the results of 

 60CO determinations of latitude in various parts of the globe. 

 The maximunr amplitude amounts to nearly half a second, which 

 corresponds to a motion of the pole amounting to 40 or 50 feet. 

 It appears that we are now approaching a period of minimum 

 amplitude. 



CHEMISTRY A 7 THE BRITISH ASSOCIA TION- 



' I "HE meeting of Section B at Oxford will be remembered as 

 one of quite exceptional interest. That portion of the 

 President's address urging upon the University fuller recogni- 

 tion of the claims of science in their curriculum will doubtless 

 have valuable results. Certain of the communications brought 

 forward in the course of the meeting m.ay be described as epoch- 

 . making. The presence of a large number of eminent foreign 

 chemists served further to render the proceedings memorable 

 and attractive. 



The Committee for preparing an International Standard for 

 the Analysis of Iron and Steel reported that their work was now 

 completed, and that it is proposed to shortly deposit^the standards 

 with the Bo.ird of Trade, or with some other suitable authority 

 where they will be at the public service. 



Prof. Clowes gave an account of his experiments on the pro- 

 portions of carbonic acid in air which are extinctive to flame, 

 ■and which are irrespirable. He finds that the flames of candles, 

 oil, paraffin and alcohol are extinguished by air containing from 

 13 to 16 per cent, of carbonic acid. The flame of coal-gas, 

 however, required the presence of at least 33 per rent, of the 

 extinctive gas, and the flame of hydrogen was not extinguished 

 mtil the amount of carbonic acid in the air reached 58 per 

 cent. Comparing his experiments with those of Mr. J. i\. 

 Wilson on the percentage of carbonic acid required to suffocate 

 a rabbit. Prof. Clowes concludes that air, containing at least 

 10 per cent, of carbonic acid more than is required to extinguish 

 a candle flame, can be breathed with impunity. By taking ad- 

 vatage of the extraordinary vitality of the hydrogen flame in 

 presence of high proportions of carbonic acid, it is possible to 

 maintain the flame of the composite safety-lamp (previously 

 described by the author), after the oil flame has been extin- 

 guished. 



Mr. Haldane concluded from some experiments he has made 

 on the respirability of air containing carbonic acid, that the 

 percentage of this gas, considered by Prof. Clowes to be re- 

 spirable, is too high. 



Much inlerest was shown in the .successful experiments of Dr. 

 Lobry de ISruyn, demonstrating the properties of free hydroxy- 

 lamine. On heating a small amount in a test-tube, a sharp 

 explosion took place. Left exposed to air, it was shown by its 

 action on iodised starch-paper to have become converted into 

 nitrous acid. In a series of test tubes its behaviour with various 

 reagents was demonstrated. With potassium permanganate, 

 and with chromic acid oxidation took place, accompanied by 

 flame ; potassium bichromate produced an explosion. The 

 anhydrous sulphates of copper and cobalt were reduced by the 

 substance. Free hydroxylamine was dissolved in anhydrous 

 ether, and sodium added, hydrogen was evolved and the very 

 ■explosive sodium compound of hydroxylamine produced. 



Chlorine and iodine were shown to act spontaneously on 

 hydroxylamine, producing inflammation. It is of interest that 

 hydroxylamine will dissolve many salts which are soluble in 

 water, the order of solubility differing in the two solvents. 



Dr. Bernthstein described a new bacterium which occurs in 

 milk, whose chief property is that of peptonising the caseine, 

 thus forming a soluble compound, and rendering the milk trans- 

 parent, and more readily digested. 



On Friday a discussion took place on the behaviour of gases 

 with regard to their electrification, and the influence of moisture 

 on their combination. It was opened by Prof. J. J. Thomson, 

 who exhibited some brilliant experiments illustrating the 

 connection between chemical change and electrical discharge 

 through gases. Tlie gases were confined, under a pressure of 

 about too mm. in glass bulbs which were placed in the centre 

 of a coil of wire connecting the exterior of two Leyden jars, 

 the interior coatings of which were connected with the two 

 poles of a Wimshurst machine. As each spark passes between 

 the poles of the machine, a rapidly alternating current is set up 

 in the coil, and hence by induction in the gas. In the case of 

 oxygen it was found that the moist gas gives a vivid incan- 

 descence, followed by an afterglow or phosphorescence, on 

 removing the bulb from the coil. With the dry gas, on the 

 other hand, incandescence does not take place. The incan- 

 descence, can however, be started in the dry gas by a brush 

 discharge, and if once started continues under the influence of 

 the induced current. With air the phenomenon is reversed ; 

 damp air does not glow, dry air will. By making use of two 

 coils in one of which was a beaker of fairly strong sulphuric 

 acid, and in the other a bulb containing moist oxygen, the 

 presence of the acid was shown to jirevent the incandescence in 

 the bulb, showing the conductivity of the gas to be much 

 greater than that of the acid. As the glow is only given in 

 gases forming polymeric modifications, it is suggested by Prof. 

 Thomson that the drops of water present may act as conductors 

 causing the original molecules to dissociate. In the case of 

 dry gases this preliminary dissociation can only be brought 

 about by expenditure of a large amount of energy. Alcohol 

 vapour will behave similarly to water, and it becomes of interest 

 to study other solvents. 



Mr. Brereton Baker followed with some experiments on the 

 influence of moisture on chemical substances. He showed 

 that ammonia and hydrochloric acid when dry do not combine. 

 He also exhibited tubes containing dry sulphur irioxide and 

 cupric o.xide, and dry sulphur trioxide and lime, side by side 

 without action upon one another, a kind of "chemical happy 

 family," as he expressed it. He concludes that the function of 

 moisture is physical rather than chemicil from the fact that on 

 heating together a dry mixture of cupric oxide, carbon and 

 oxygen, no action takes place. He has obtained analogous 

 results to Prof. Thomson, by using semi-vacuous tubes, into 

 one end of each of which a platinum wire is fused and which 

 contain a small quantity of mercury. On shaking these tubes 

 in a dark room incandescence takes place in those containing 

 moist oxygen. This is less if nitrogen is present, and ceases if 

 the gas is dry. It was resolved in committee that i'rof. 

 Thomson's and Mr. Baker's papers should be published in full. 

 Dr. Ewan read a paper on the rate of oxidation of phos- 

 phorus, sulphur and aldehyde, a portion of which h.as already 

 appeared in Nature. The results obtained with aldehyde are 

 free from the uncertainty produced by the correction for the 

 changing rate of evaporation. When proper precautions are 

 taken this reaction goes perfectly regularly at 2C^ and its 

 velocity is proportional to the product of the pressure of the 

 aldehyde and the square root of the pressure of the oxygen. 

 These results are most simply explained by assuming (in 

 accordance with Williamson's theory), that the oxygen first 

 splits up to some small extent into atoms, and that these alone 

 take part in the oxidation. 



In the discussion which followed the reading of these papers. 

 Prof. .Schuster spoke of the difficulty experienced in passing a 

 discharge through mercury vapour. 



Prof. Pringsheim noted the importance of ascertaining the 

 relation between the spectrum given by the discharge, and that 

 of the after-glow in the gas. 



Mr. Vernon Ilarcourt remarked that Mr. Baker's results 

 show that the part played by water in these reactions is prob- 

 ably unique, and is not shared by many, if any, other 

 substances. 



With reference to the dissociation of molecules, Mr. Baker 



NO. 1295, VOL. 50] 



