584 



NA TURE 



[October 15, 1896 



lion and estimation of carbon monoxide in air, with about the 

 same degree of sensitiveness as with acetylene. A short note on 

 "The Accurate Estimation of Oxygen by Alworption with Alka- 

 line Pyrogallol Solution" was also read by I'rof. Clowes. 



Dr. A. \V. Titherley, of University College, Liverpool, gave 

 a short account of his work on the "Amides of the Alkali 

 Metals and some of their Derivatives." The amides of sodium, 

 potassium, lithium, and rubidium have been prepared in the 

 ]iure stale. They all readily dissolve the corresponding metal, 

 forming blue solutions. Their melting points do not vary regu- 

 larly with the atomic weight of the metal, since lithamide melts 

 at 380-400", sodamide at 155°, pota.ssaniidc at 270°, and rubid- 

 amide at 285°. The potassium and sodium compounds do not 

 yield the nitride when heated, as has been slated by previous in- 

 vestigators. Analogous derivatives of the alkyl amines have also 

 been prepared, and promise to be of great interest. 



Several communications on physical chemistry were received 

 by the Section, the first of which was a paper by Prof. Oscar 

 Liebreich, on " Diminution of Chemical Action due to Limita- 

 tions of Space." Certain reactions take place much less readily 

 near a liquid surface than in the interior of a liquid, and the 

 author terms this region of diminished action the " dead space." 

 This remarkable fact has led the author to the conclusion that 

 liquid friction is of influence on the phenomena of chemical 

 action, and that in small enclosed spaces— spaces in which the 

 fluid is, as it were, solidified — the reaction is retarded. 



Dr. Wildermann read a paper supplementing that which he 

 brought before the Association at its last meeting on "The 

 Velocity of Reactions before perfect Equilibrium takes place." 

 For a number of cases of crystallisation of liquids and solutions 

 he has now been able to olitain experimental evidence which 

 e.stablishes the complete applicability of the thermodynamic 

 equation to the rale of reaction, as well as to provide a statical 

 explanation for the well-known fact that the velocity of a 

 reaction is independent of the amount of a solid substance 

 present, which cannot readily be explained on kinetic grounds. 



In a short note on "The Behaviour of Litmus in Amphoteric 

 Solutions," Dr. T. Bradshaw opposed the view that the violet 

 colour produced when a mixture of sodium dihydrogen phosphate 

 with the ordinary disodium hydrogen phosphate is added to a 

 solution of litmus is due to a special compound, probably an 

 acid salt, of the litmus acid. The author considers thai the violet 

 colour is caused by the simultaneous presence of small amounts 

 of blue and red litmus, the shade varying with the proportions 

 of the two sodium salts which are present, whilst taken separately 

 one of the salts has an acid, and the other an alkaline reaction to 

 litmus. 



Prof. Max Bamberger read a short paper on " Excrescent 

 Resins," and described a number of crystalline substances which 

 he had succeeded in extracting from them. Messrs. A. G. Green 

 and A. Wahl contributed a paper on "The Constitution of Sun 

 Yellow or Curcumine and allied colouring matters." These 

 substances have been supposed by Bender to contain the azoxy- 



group — N' — ^N — , but this does not account for the great 

 stability of the compounds towards oxidising agents, nor for the 

 difficulty of reduction to diamidostilbenesulpihonic acid. These 

 |iroperties are better explained by supposing that one of the 

 nitrogen atoms is present as an azine group, whilst the other 

 acts as a pentad and is combined with oxygen, the characteristic 



C-=NO^C 

 ring, I I being therefore present. It appears probable 



C = N— C 

 that oxyphenine, chloramine yellow, and other dyes have a similar 

 constitution. 



Dr. F. E. Francis read an interesting paper on " Abnor- 

 malities in the behaviour of Ortho-derivatives of Orthamido- 

 and Orthonitro-benzylamine," in which he drew attention to 

 ihe remarkable influence on the behaviour of certain compounds 

 of the presence of substituted groups in the ortho-position. 

 Thus, for example, whilst most of the derivatives of orthamido- 

 benzylamine yield a triazine when treated with nitrous acid, no 

 such compound can be obtained from the orthamidobenzyl 

 derivatives of orthotoluidine, orthanisidine, and orthochlorani- 

 line. A number of other instances were also adduced. 



In a paper on " Nitrates : their Occurrence and Manufacture," 

 Mr. W. Newton, after describing the ordinary method of 

 extracting sodium nitrate, drew attention to the fact that the 

 rocky stratum overlying the caliche contains 15 to 20 per cent, 

 of nitrate, and that, although this has to be broken through 



before the caliche can be removed, the whole of the nitrate in 

 it is at present neglected. The total production of nitrate, 

 which was only 58,000 tons in i860, amounted to 1,218,000 

 tons in 1S95. 



Prof Ramsay gave a detailed account of the very remarkable 

 and abnormal properties of helium. When this gas is fraction- 

 ally diftused through a piece of pipe-stem, it may be separated 

 into two portions, which differ in density, one of them having 

 the density I "874 and the other 2-133. These two portions 

 nevertheless show exactly the same spectrum when they are 

 examined under the same conditions, the difference between the 

 spectra of the two fractions, which was observed by Runge and 

 Paschen, being due to a difference of pressure. The refractive 

 indices of the two portions are directly proportional to their 

 densities, whilst this relation does not hold for other gases. A 

 further abnormality exists in the rates at which the two fractions 

 diffuse. The relative rate of diffusion of each fraction, compared 

 with hydrogen, is about 15 to 20 per cent, more rapid than that 

 calculated from the density, according to Graham's law. No 

 satisfactory explanation has yet been arrived at, and the author 

 proposes to submit other gases to fractional diffusion, in order 

 to see whether they also yield two fractions of different density. 

 Such a result would seem to point to the conclusion that the 

 atoms of any substance are not all alike in weight, but vary 

 about an average value, as suggested by Crookes. In the dis- 

 cussion which followed, Prof. Dixon [lointed out that Graham's 

 law of diffusion is based solely on experiments made with gases 

 composed of polyatomic molecules. The President suggested 

 that, as both helium and argon have no chemical affinities, it is 

 not extravagant to look upon them as the first examples of 

 a new kind of matter, differing in many respects from ordinary 

 matter. 



Dr. F. Hurler, in a paper on the " Manufacture of Chlorine 

 by means of Nitric Acid, touched upon a phase in the develop- 

 ment of the chlorine industry which had only been lightly 

 treated in the presidential address. The principle of all the 

 methods ]iroposed for this purpose is the decomposition of 

 hydrochloric acid by nitric acid, with the ultimate production of 

 an oxide of nitrogen and free chlorine. The oxide of nitrogen 

 is then reoxidised to nitric acid, and the process thus rendered 

 continuous. All the methods hitherto proposed for this purpose 

 labour under the fatal disadvantage that the treatment involved 

 necessitates the concentration of a very large amount of sulphuric 

 acid, the expense connected with which is fatal to the economical 

 conduct of the process. The great difficulty of finding a 

 material which will withstand the strong acids employed was 

 brought forward by Mr. E. K. Muspratl as a further objection 

 to the process. 



Prof. J. Dewar gave an interesting account of several points 

 in connection with "Low Temperature Research." Owing to 

 the relative pressures of oxygen and nitrogen in the air, these 

 two gases, although possessing different boiling-points, condense 

 at almost exactly the same temperature when air is cooled. 

 The method employed for measuring low temperatures consists 

 in using a system of five thermo-junctions, so arranged that 

 three of them are kept at 0°, whilst the other two are of the 

 same metals but in the inverse order, so that when one of them 

 is cooled, the other must be heated in order to preserve 

 equilibrium. The low temperature to be observed is thus 

 balanced by a high temperature which can easily be read off. 

 Helium appears to be less easily condensible than hydrogen, 

 and, moreover, possesses an abnormally low refraclivity and 

 real molecular volume. It is a remarkable fact that fluorine, 

 the most active of all the chemical elements, in these respects 

 resembles helium, the least active of all. The ratio of the 

 refraclivity of hydrogen to that of chlorine is almost the .same 

 as that of helium to that of argon, and it is quite possible that 

 a substance may yet be discovered which will be intermediate 

 between these two elements, just as fluorine is intermediate 

 between hydrogen and chlorine. 



A new and convenient form of Schriitter's apparatus for the 

 estimation of carbon dioxide was exhibited by Dr. C. A. Kohn, 

 who also, in conjunction with Dr. T. L. Bailey, showed an 

 aspirator worked by a small electric motor. Dr. J. Ilaldane 

 gave an interesting demonstration of his colorimetric method of 

 estimating small amounts of carbon monoxide in the air, which 

 has recently been described in Nati'ki; (vol. liv. p. 207). 

 Chemists will be interested to learn thai the continued inhala- 

 tion of a small proportion of the gas is much more dangerous than 

 the momentary reception of a large quantity of it into the 



NO 1407, VOL. 54] 



