70 



NATURE 



[November 17, 1892 



must be expressed in terms of a unit of the same kind as itself. 

 He viewed Mr. Williams's attempt to express everything in terms 

 of L, M and T, as rather a retrograde step. The discussion on 

 Mr. Williams's paper was adjourned, and Dr. Young made some 

 remarks on Mr. Sutherland's communication " On the Laws of 

 Molecular Force." Mr. Sutherland, he said, thought that Ramsay 

 and Young's law d//9T -f{v) is not correct for compounds in the 

 liquid state. Barus, however, had proved that several liquids, 

 including ether, only showed variations from the law at ex- 

 tremely high pressures. After writing the equation of the virial 

 in the iorm pv = KYvf{v) +v<l>{v), where V(p{v) stands for the 

 internal virial term ; the author of the paper had shown that 

 7j^<p{v) ought to be constant, but, finding it not constant in the 

 case of ether, &c., he attempted to explain the discrepancies by 

 the formation of pairs of molecules at small volumes. Other 

 substances, such as nitrogen and methane, were supposed to 

 follow the law. This, Dr. Young said, could not be accepted 

 as proved, for the range of volumes over which the experiments 

 had been made was only small, and methane was difficult to pre- 

 pare pure. After criticizing the use of two and sometimes three 

 " characteristic equations" for the same substance, he went on to 

 show that the formulae given in the paper by which the critical 

 temperatures, pressures and volumes lAight be calculated, lead 

 to results differing from experimental numbers by quantities 

 greatly in excess of experimental errors. Experiment also 

 showed that capillarity had little or no effect on the determina- 

 tion of critical constants. Speaking of critical volumes he 

 pointed out that MM. Cailletet and Mathias had published a 

 method of finding critical densities which gave very accurate 

 results. Mr. Sutherland's conclusions respecting Van der 

 Waals's generalizations were practically identical with those 

 expressed by Dr. Young in his paper on the subject, read before 

 ■the Society last year. The views as to the nature of the various 

 kinds of "pairing" mentioned in Mr. Sutherland's paper were 

 open to serious objections, for his "physical pairing" is sup- 

 posed to produce more effect on the " characteristic equation " 

 than true chemical pairing. In his (Dr. Young's) opinion the 

 idea of physical pairing appears somewhat speculative and 

 requires further elucidation. — A paper on the determination of 

 the critical density, by Dr. Young and Mr. A. L. Thomas, and 

 two papers, on the determination of the critical volume, and on 

 the boiling points of different liquids at equal pressures, by Dr. 

 Young, were taken as read. The first paper gives an account 

 of results obtained by Cailletet and Mathias's method, based 

 on the fact that the means of the densities of a substance in the 

 states of liquid and saturated vapour when plotted with tem- 

 perature, lie on a straight line which passes through the critical 

 point. In the paper on critical volumes the above-mentioned 

 method is again referred to and results obtained thereby 

 accepted in preference to those given by the author in his paper 

 on Generalizations of Van der W^aals, &c., read before the 

 Society about a year ago. The alcohols do not strictly follow 

 the straight-line law. Revised tables of critical volumes, 

 densities, pressures, and temperatures are given, and it is 

 pointed out that for many substances the ratio of the actual critical 

 density to the theoretical density (for a perfect gas) is about 3*8. 

 The paper on boiling-points of different liquids at equal pres- 

 sures contains a comparison of the accuracies with which a 

 formula for the relation between the boiling-points given by M. 

 Colst {Compt. Rend., cxiv. p. 653), and one by Ramsay and 

 Young {Phil. Mag., January 1886), accord with experimental 

 results. The author concludes that the latter formula shows 

 the best agreement, but that of M. Colst is satisfactory under 

 certain conditions. The further discussions of Mr. Williams's 

 and Mr. Sutherland's papers were adjourned till the next 

 meeting. 



• Mineralogical Society, October 25.— At the Anniversary 

 Meeting the following were elected Officers and Members of 

 Council :— President, Prof. N. S. Maskelyne, F.R.S. ; Vice- 

 Presidents, Rev. Prof. S. Haughton and Dr. Hugo Miiller, 

 F.R.S. ; Treasurer, Mr. F. W. Rudler, F.G.S.; General Secre- 

 tary, L. Fletcher, F. R. S. ; Foreign Secretary, Mr. T. Davies ; 

 Ordinary Members of Council, Prof. A. H. Church, F.R.S., 

 Prof. Grenville A. J. Cole, Mr. T. W. Danbv, Dr. C. Le 

 Neve Foster, F.R.S., the Rev. H. P. Gurney, Mr. J. 

 Home, Prof. J. W. Judd, F.R.S., Prof. G. D. Liveing, 

 F.R.S., Lieut. General C, A. McMahon, Mr. H. A. Miers, 

 Mr. F. Rutley, and Mr. J. J. H. Teall, F.R.S.— Dr. C. O. 

 Trechmann detailed the results of the goniometrical measure- 



NO. T203. "^OL. 47] 



ment of two very perfect crystals of Binnite collected by 

 himself in the Binnenthal. The measurements, besides adding 

 a large number of forms to those previously recorded for this 

 species, serve to establish the tetrahedfal hemisymmetry of the 

 mineral which has been left as a very doubtful feature by pre- 

 vious observers, and was denied by Hessenberg. — Mr. H. A. 

 Miers and Mr. G. T. Prior announced the results of further 

 researches on the rare silver minerals known as Xanthoconite 

 and Rittingerite. According to their physical measurements 

 and chemical analyses these two substances are identical, both 

 having the same composition as Proustite, and crystallizing in 

 rhombic -shaped tables belonging to the mono-symmetric system. 

 The name Xanthoconite, given by Breithaupt, has the priority ; 

 the red-silver ores are now to be regarded as an isodimorphous (?) 

 group consisting of the two sulph-arsenites Proustite and Xan- 

 thoconite, and the two sulph-antimonites Pyrargyrite and Fire- 

 blende. Previous determinations of the composition of Rittin- 

 gerite and the crystalline form of Xanthoconite have been 

 erroneous. — Mr. Fletcher gave a description of a new habit of 

 Descloizite from the Argentine, and also an account of the new 

 mineral Baddeleyite (native zirconia) : the only fragment as yet 

 found is part of a twinned crystal showing forms which belong to 

 the mono-symmetric system : pleochroic : optically negative 

 and biaxal with inclined dispersion: specific gravity 6*025 : 

 hardness 6-5. — Mr. Allan Dick contributed further remarks on 

 Geikielite, supplementing his paper read at the previous meet- 

 ing.— Prof. Judd exhibited photographs in illustration of his 

 previous paper on the lamellar structure of quartz crystals and 

 the method by which it is developed. —Mr. Rutley exhibited a 

 large series of beautiful cardboard models illustrative of the 

 symmetry and optical characters of the crystalline systems. — 

 Mr. Miers exhibited specimens, including the rare mineral Tur- 

 nerite from the I'intagel Slate quarries which he had visited in 

 search of that mineral. 



Zoological Society, November i. — Sir W. H. Flower, 

 F.R.S., President, in the chair.— The Secretary read a report 

 on the additions that had been made to ihe Society's Menagerie 

 during the months of June, July, August, and September, 1892, 

 and called special attention to a young Gibbon from Hainan, 

 South China, of a uniform black colo ir, belonging to the 

 specie'! recently described by Mr. Oldfield Thomas as Hylobates 

 hainanus, presented by Mr. Julius Neumann, and to a young 

 male Malayan Tapir {Tapirus tndicus) horn T&yoy, Burmah, 

 presented by Col. F. M. Jenkins.— Mr. E. Hartert exhibited 

 (on behalf of the Hon. Walter Rothschild) examples 

 of two new Mammals from New Guinea {Proechidna nigro- 

 aculeata and Acrobates pulchellus), and a stuffed specimen of 

 Apteryx maxima from Stewart Island. — A communication was 

 read from Lord Lilford, giving an account of the breeding of a 

 pair of Demidoffs Galagos in his possession. — Prof. Bell read 

 a note on the occurrence of Bipaliuin keivense in Ireland. — 

 Mr. Finn gave an account of his recent zoological excursion to 

 Zanzibar. — Prof. Newton, F.R.S., exhibited and made remarks 

 on a specimen of .Sy/zfrn nisoria lately killed in England. — Prof. 

 F. Jeffrey Bell read a description of a remarkable new species 

 of Echinoderm of the genus Cidaris from Mauritius, proposed 

 to be called C. curvaii^pinis. — A communication was read 

 from Sir Edward Newton, and Dr. Gadow, F.R.S., describing 

 a collection of bones of the Dodo, and other extinct birds of 

 Mauritius, which, having been recovered from the Mare aux 

 Songes in that island by the exertions of Mr. Theodore Sauzier, 

 had been by him entrusted to them for determination. The 

 collection contained examples of the atlas, metacarpals, pre- 

 pelvic vertebra, and complete pubic bones of the Dodo, which 

 had before been wanting, as well as additional remains of 

 Lophopsittaais, Aphanapteryx, and other forms already known 

 to have inhabited Mauritius. Besides these there were bones 

 of other birds, the existence of which had not been suspected, 

 and among them of the following, now described as new : — 

 Strix (?) saitzieri, Astur alphonsi, Butorides mauritiamis, 

 Plotus nanus, Sarcidiornis maiiritianus and Anas theodori, the 

 whole adding materially to the knowledge of the original fauna 

 of Mauritius. — Mr. Oldfield Thomas gave an account of a col- 

 lection of Mammals from Nyassa-land, transmitted by Mr. H. 

 H. Johnston, under whose directions they had been obtained 

 by Mr. Alexander Whyte. — Dr. Giinther, F.R.S., read a paper 

 descriptive of a collection of reptiles and Batrachians from 

 Nyassa-land, likewise transmitted by Mr. Johnston, and con- 

 taining examples of several remarkable new species, amongst 

 which were three new Chameleons, proposed to be called 



