April io, 1902 



NA TURE 



547 



of the genus Mallomonas permit the author to establish a classi- 

 fication of this difficult division. — A new archaic inscription of 

 ihe Roman forum, by A. Enmann. 



Bulletin dii Jardin Cota)iii:iis de St. P^'tersbourg, tome ii. 

 fasc. i. — On the causes of the absence of wood on the yailas 

 (high mountain plateaus) of Crimea, by G.J. Tanfiljew. Thecause 

 is probably in the late thawing of snow — often in May only — and 

 the consequent saturation of the soil with water.- — Lichenological 

 notes, by A. A. Elenkin. - Communications. 



Memoirs of the A'oi'orossian (Odessa) Society of Naturalists, 

 vol. -xxiii., 2. — Remarks on the Crimean stag, by A. Brauner 

 (two plates). Unlike Ward, Nikolsky and Lydekker, the author 

 considers this stag as C. elaphti'., L. , which is near, not to the 

 typical individuals from the forests, rich in food, of middle 

 Europe, but to the island type (also mountain and southern 

 type), and especially to the Corsican representative of this species 

 (summary in German). — On the nitrification of water, by 

 E. Gredig. — Note on the Sarmatian deposits of Transcaucasia, 

 by V. Lashkarev, on the basis of Prof. Ernest Favre's collection 

 at Geneva.-^Fauna of the caves of Crimea, by J. Lebedinski, 

 with one plate. First attempt to explore these caves. 



SOCIETIES AND ACADEMIES. 

 London. 

 Royal Society, November 28, 1901. — "Micro-crystalline 

 Structure of Platinum." By Thomas Andrews, F. R. S, 



The crystalline structure of platinum does not appear to have 

 been studied, although it forms an interesting subject for in- 

 vestigation. A small ingot of pure platinum was obtained for 

 the experiments. A section was cut therefrom and machined 

 to 5/l6th inch square and l/ioth inch in thickness. The section 



)-crystaIUne structure of pla 

 360 diameters. 



was then carefully polished and etched in aqua regia. The 

 etching was very dilticult and required the greatest care in 

 manipulation to satisfactorily develop the crysialline structure. 

 The result of the etching was the development of a beautiful 

 crystalline structure which manifested, not only the large or 

 primary crystal grains, but also the secondary or very minute 

 crystalline development which is illustrated on a plale ac- 

 companying the paper, as seen in section at magnifica- 

 tions respectively of 50, 120, 360 and 360 diams. The 

 last two of these figures are here reproduced. The larger 

 or primary crystal grains were observed to consist of irregular 

 pol)gons of varying size, the etched indications of the 

 facet junctions being often clearly and sharply defined. The 

 minute or secondary crystals (whose intercrysialline junctions 

 were also clearly seen) were in the mass observed to be in varied 

 positions of orientation, but the orientation was generally 

 identical, or on the same plane, within the area of each larger 

 crystal grain. The general orientation of the smaller crystah 

 varied, however, in each separate larger crystal, and the conse- 

 quent varied reflection of the light has given the face of the 



NO. 1693, VOL. 65] 



microsections, as a whole, the appearance of lighter or darker 

 areas in the photomicrographs. In some portions of the mass 

 there were observed minute triangular crystals ; these appear, 

 however, to be only developments resulting from the cutting of 

 certain crystals in section. The general microcrystalline struc- 

 ture of platinum was observed to be allotriomorphic in character 



360 d 



and derived from a system of interfering cubes and oclahedra, 

 the cubic and hexagonal form being frequently noticeable. The 

 size of the large crystal grains varied from about o'002 inch to 

 004 inch in size, and the smaller crystals ranged from about 

 o'ooo2 inch to about O'oo? inch. There were indications that 

 the smaller or secondary crystals were each built up of even 

 more minute crystalline ramifications. The crystalline structure 

 of platinum appears to generally resemble that of gold and silver. 

 The descriptive words "primary" and "secondary" crystals 

 Lire only used in relation to size, and they are not intended to 

 convey the idea of distinctive times of formation during 

 solidification. 



February 13. — " Preliminary Note on a Method of Calcu- 

 lating Solubilities and the Equilibrium Constants of Chemical 

 Reactions, and on a Formula far the Latent Heats of Vaporisa- 

 tion." By Alexander Findlay, M.A., B.Sc, Ph.D. Com- 

 municated by Prof. Ramsay, F.R.S. 



If R and R' represent the ratios of the absolute temperatures 

 at which two substances have the same solubility, the author 

 shows that R = R' 4- c (t' -t), where r is a constant having a 

 small positive or negative value and /' and / are the tempera- 

 lures at which one of the substances has the two values of the 

 solubility in question. The formula is precisely similar to that 

 which Ramsay and Voung showed to hold in the case of vapour 

 pressures (/%i7. A/ax , 18S6, xxi. 33). Given the solubility 

 curve of one substance it is therefore possible to calculate the 

 solubility of a second substance provided the solubility of the 

 latter at two temperatures is known. The author shows that 

 this method can be applied to the calculation of "equilibrium 

 constants " of chemical reactions. 



It is further shown that if L, is the known latent heat of 

 vaporisation at the absolute temperature T, of one substance, 

 and Lothe latent heat of the second substance at the temperature 

 T.J at which the vapour pressure of the second substance is equal 

 to that of the first at the temperature T,, then L,/L,, = T^'^/T^'^. 

 A less exact, but simpler formula is L, = L,.{T/. These formulae 

 appear not to be applicable when the pressure exceeds 

 fo,ooo- 20,000 mm. 



February 20. — "On a Pair of Ciliated Grooves in the 

 Brain of the Ammoccete, apparently serving to promote the 

 Circulation of the Fluid in the Brain-cavity.'' By Arthur 

 Dendy, D. Sc, F. L. S. , Professor of Biology in the Cant;r- 

 bury College, University of New Zealand. Communicated by 

 Prof. G. B. Howes, F.R S. 



The author demonstrates the existence in the brain of the 

 Ammoccete of a pair of remarkable ciliated grooves. The 

 structures in question were discovered by the author in the 



