March 28, 1901] 



NATURE 



529 



ture from the sine form, up to I7,(X)0. The methods and special 

 instruments for ihe exact measurement of these currents are also 

 given. — The acoustical and electrical properties of the telephone, 

 by Max Wien. — On the theory of rain precipitation in moun- 

 tains, by F. Pockels. The conclusion is drawn from theoretical 

 considerations that on the slope of a mountain chain there 

 exists a zone of maximum precipitation, and that the inclination 

 as well as the absolute height has an effect upon the amount 

 precipitated. Both these conclusions are in agreement with 

 observations upon the higher mountains. — The effect of current 

 fluctuation, of electrical oscillations, and of an induced current 

 upon a magnetic needle placed in a constant field, or upon a 

 small soft iron inductor, by Max Hornemann. — Some results 

 of capillarity phenomena, by A. Einstein. — On the so-called 

 liquid crystals, by G. Tammann. It is shown that the effects 

 produced by the so-called liquid crystals may be explained by 

 the assumption that there is really present a mechanical mix- 

 ture of two liquids. A partial separation was effected in the 

 case of /5-azoxyanisol. — On some experiments with the Becquerel 

 and Rontgen rays, by F. Himstedt. The sparking distance for 

 an influence machine is affected by both the radium rays and 

 the Rontgen rays. The failure of Elster and Geitel to observe the 

 1 itter effect is attributed by the author to the use of too small a 

 Crookes' tube. — On the action of the Becquerel and Rontgen 

 rays on the eye, by F. Himstedt and W. A. Nagel. — On the law 

 of the distribution of energy in the spectrum, by Max Planck. — 

 On the elementary quantity of matter and of electricity, by Max 

 Planck. — Studies in hardness, by W. Voigt. — On characteristic 

 curves in the electrical discharge through rarefied gases, by E. 

 Riecke. — Experimental researches on the metallic reflection of 

 electrical oscillations, by Karl F. Lindman. — On the distribu- 

 tion of electricity on an ellipsoid, by H. Dorrie. — On the 

 transparency of hydrogen to light, by V. Schumann. — On the 

 fundamental hypothesis of the kinetic theory of gases-, by S. H. 

 liurbury. — Remarks on the paper of E. v. Schweidler on the 

 behaviour of liquid dielectrics on the passage of an electric 

 current, by E. Warburg. 



SOCIETIES AND ACADEMIES. 

 London. 

 Physical Society. —Meeting held in University College, 

 March 22. — Prof. S. P. Thompson, president, in the chair. — 

 A paper on the expansion of silica was read by Prof. Callendar. 

 The extreme smallness of the thermal expansion of silica (fused 

 quartz) renders the determination of its coefficient of expansion 

 more difficult than is the case with many substances. The 

 author has made experiments upon a rod of pure silica 40 cms. 

 long and i mm. diameter. This rod was enclosed in a platinum 

 tube about 3 mms. diameter, which could be raised to various 

 temperatures by the passage of a suitable electric current. Both 

 the rod and the tube were firmly fixed at one end, and the 

 positions of the other ends were accurately observed by a 

 micrometer microscope reading to a thousandth of a mm. The 

 expansion of the tube, in conjunction with a knowledge of its 

 coefficient of expansion, served as a means of determining the 

 temperature of the tube, and, therefore, of the rod. The in- 

 crease in length, the original length and the range of tempera- 

 ture of the silica being known, the coefficient of expansion can 

 be at once calculated. In some previous experiments the author 

 has investigated the distribution of temperature along a heated 

 platinum rod subjected to cooling at the ends. These experi- 

 ments prove that the error due to end effect, in the case of the 

 silica rod, can be neglected. The expansion of silica up to 

 1000° C. is regular, and is about one-seventeenth that of 

 platinum. Between 1000° C. and 1400° C. silica expands more 

 quickly than below 1000° C, and if left at any temperature for 

 a considerable time continues to slowly increase in length. If 

 a curve be plotted having temperatures as abscissae, and in- 

 creases in length as ordinates, a straight line will represent the 

 expansion of silica up to 1000° C. Above 1000° C. the curve 

 bends upwards, and upon cooling it returns along a path above 

 the ascending curve, so that the final length of the bar is greater 

 than the original length when the lower temperature is reached. 

 The determination of the coefficient of expansion at these high 

 temperatures was made by means of a variable zero, that is by 

 using for the length of the rod that obtained by suddenly cooling 

 from the higher to the lower temperature. At 1400° C. the 

 properties of silica alter and the expansion is replaced by a 

 contraction. On cooling from above 1400° C. to ordinary 



NO. 1639, VOL. 63] 



temperatures there is first an expansion and then a contraction. 

 This property was illustrated by Prof. Callendar, the small 

 changes in length of the rod being magtiified by a lever and 

 shown upon a screen by an optical arrangement. The critical 

 point at which contraction occurs on heating has been found by 

 Le Chetalier at about 800° C. His experiments were made by 

 a differential metho'', using porcelain as a standard sulistance. 

 As the expansion of p )rcclain is uncertain, the author thinks it 

 probable that the eflcct noticed may be due to irregularities in 

 the expansion of porcelain rather than in that of silica. Mr. 

 Boys expressed his interest in the experiments and asked if the 

 small coefficient of expansion of slate had ever been measured. 

 The small expansion of silica would make it a useful suspension 

 for pendulums on account ot the small compensation necessary. 

 Its perfect elastic properties might be made use of in hair springs 

 for chronometers. Prof. Threlfall said that he had tried to 

 measure the expansion of silica between 0° C. and 70° C. by 

 weighing rods in distilled water, but the method was not 

 accurate. He had made experiments similar in principle to the 

 author's, using temperatures from 0° C. to ICX3° C. The devitii- 

 fication of silica is troublesome, and he thought that the rate of 

 devitrification in presence of air increased with the temperature. 

 Dr. Donnan thought that the irregularities in the expansion of 

 silica p:jinted to a complex composition. Mr. Porter (Eton), 

 asked if the effect ot fused quartz on polarised light had been, 

 investigated, and if this effect altered after heating to 1400° C. 

 Mr. Boys said that quartz rods formed by fusion depolarised- 

 light. The chairman said that he had noticed the effect spoken 

 of by Mr. Boys, due to strain, but he had been unable to detect 

 any rotatory power. Prof. Callendar, in reply to Mr. Lupton, 

 said that the expansion of quartz crystals was much larger than 

 that of fused silica.— The spectroscopic apparatus of University 

 College was then exhibited by Dr. Baly. — The Society then 

 adjourned until April 26. 



Chemical Society, March 7. — Dr. Perkin, vice-president, in. 

 the chair. — The following papers were read : — Nomenclature of 

 the acid esters of unsymmetrical dicarboxylic acids, by J. J. 

 Sudborough. — Additive compounds of a- and )3-naphthylamine 

 with trinitrobenzene derivatives, by J. J. Sudborough. The 

 author describes a number of additive compounds of red or 

 purple colour which are formed from derivatives of trinitro- 

 benzene and the naphthylamines, and are more stable than such 

 compounds as those of trinitrobenzene and aniline. — Acetylation. 

 of arylamines, by J. J. Sudborough. It is shown that the pre- 

 sence of orthosubstituents, whether of positive or negative 

 character, accelerates the formation of diacetyl derivatives of 

 primary arylamines. — Formation of amides from aldehydes, by 

 R. H. Pickard and W. Carter. On oxidising an aldehyde with 

 ammonium persulphate in presence of lime, a 30 to 40 per cent, 

 yield of the amide of the corresponding acid is obtained. — A 

 method of isolating maltose when mixed with glucose, by A. C. 

 Hill. The author gives a method for separating maltose from 

 a mixture of glucose and maltose based upon the fact that 

 Saccharomyces marxianus destroys the former, but leaves th6 

 maltose untouched during its growth in a solution of the mixed 

 sugars. — The vapour pressure of aqueous ammonia solutions, by 

 E. P. Perman. The author has determined the vapour pres-^ 

 sures of aqueous ammonia solutions between the temperatures- 

 0° and 60°, and for concentrations up to 35 per cent. — The in- 

 fluence of sodium sulphate on the vapour pressure of aqueous 

 ammonia solution, by E. P. Perman. The vapour pressure 

 curves of aqueous ammonia containing sodium sulphate afford 

 no indication that the latter exists as a hydrate in the solution, 

 — Formation of aromatic compounds from ethyl glutaconate and 

 its derivatives. The reduction of trimesic acid and the converT 

 sion of tetrahydrotrimesic acid into tetrahydroisophthalic add, 

 by W. T. Lawrence and W. H. Perkin, jun. Ethyl sodiodi- 

 carboxyglutaconate, (COOEt)2CNa.CH : C(COOEt)2, heated 

 with alcohol at 150°, yields ethyl trimesate, and ethyl gluta- 

 conate, under similar conditions, is converted into a substance 

 which on hydrolysis gives hydroxyisophthalic acid. Trimesic 

 acid is reduced by sodium amalgam to a mixture of stereoiso- 

 meric tetrahydrotrimesic acids, of which one has been isolated 

 in a pure state ; this gives a double anhydride with acetic an- 

 hydride, which, when distilled, yields tetrahydroisophthalic an- 

 hydride. — Optical activity of certain ethers and esters, by P. A. 

 Guye. — Halogen-substituted thiosinamines, by A. E. Dixon.- 

 The author describes a number of chloroallylthiocarbimides. — 

 A form of tautomerism occurring amongst the thiocyanates of 

 electro-negative radicles, by A. E. Dixon. 



