594 



NATURE 



[April 21, 1 88 1 



by M. Alexeeff. — On the rotation of Jupiter, by M. Kortazzi. — 

 Crystals of beryl from a part of the Southern Oural, by M. 

 Kol^scharow. — On the formation of some nitrated derivatives of 

 some hydrocarbons of the fatty series by direct action of nitric 

 acid, by M. Konowalof. — On the variability of forms of Liibo- 

 niirskia Baicalatsis, and on the distribution of sponges of Lake 

 Baikal, by M. Dybowski. — On universal time, and on the choice 

 for this purpose of a prime meridian, by M. Struve. — Anatomy 

 of the lactiferous glands during the period of lactation, by M. 

 Saefftigen. — On the spectroscopy of hydrogen, byM. Hasselberg. 



Heale Istitnto Lombardo di Scienze e Lcttere. Rendkoiiti, 

 vok xiv. fasc. 4 (February 24). — On a method of finding with 

 the microfcope the adulterations of the more common varieties 

 of farina, by Dr. Cattared.— Experimental researches with the 

 Crookes' apparatus, by Prof. Ferrini. — On a quadratic Cre- 

 monian correspondence between the elements of two fundamental 

 forms of the fourth species, or ruled spaces, by S. Aschieri. — 

 Considerations on new species of partial blindness in Arachnida, 

 by Prof. Pavesi. 



Fasc. 5. — Materials to serve for t)ie study of Peronospora 

 viiicola, by Count Trevisan. — On primary and secondary psoitis, 

 by Prof. Sangalli. — The sanitary administration in Spain, by 

 Dr. Quechi. — Determination of the maximum moments due to 

 vpeights linked on a supported beam, by Prof. Clericetti. — On 

 an abnormal case of fructification in Floridece, by S. Ardissone. 



Ri-ijue Internationale des Sciences, February, 1881. — Prof. 

 Vulpian, physiological study of poisons, vii. Curare (end). — 

 Prof. R. Lankester, embryology and classification of animals. — 

 Fernand Lataste, a few more words on the fecundation of the 

 urodele batrachians. — Notices of learned societies. — Belgian 

 Academy (abstract of Van Bambeke's paper on the formation of 

 the emhryonic lamellie and the notochord in theurodela). — Paris 

 Academy : on the appointment of M. Bouley to the Chair of 

 Comparative Pathology at the Natural History Museum, Paris. 



Journal de Physique, March. — On the division of instanta- 

 neous currents (continued), by M. Brillouin. — On the psychro- 

 meter, by M. Angot. — New tourmaline pincer, by M. Bertin. — 

 Constitution of the flame of the Bunsen lamp, and some modifi- 

 cations in the construction of this lamp, by M. Terquem. — 

 On some experiments in acoustics, by M. Neyreneuf. 



Atti della R. Accademia dei Lincei, vol. v. fasc. 7 (March 6). 

 — On solar observations at the Koyal Observatory of the Roman 

 College in 1880, by P. Tacchini. — Observations of comets and 

 planets at the same college with the Merz equatorial, during 

 1S80, by the same. — M. Janssen's solar photojjraphs taken at 

 Meudon Observatory, by the same. — Thermal laws of the 

 exciting spark of condensers, by E. Villari. — On sodio-ammo- 

 niacal trimolybdate, by F. Mauro. — Studies on rotatory power, 

 by R. Inasinio. — On some compounds of the pyrolic series, 

 by L. G. Ciamician. — On the electrophorus, by G. Govi. 

 — On pathological bases, by F. Selmi. — On the causes of 

 distinctness in solar photographs, by S. Respighi.— On experi- 

 ments made at the Observatory of Campidoglio for determina- 

 tion of gravity, by the same. 



Sitzungsberichte der natunvissenschaftlichen Gesellschaft /sis in 

 Dresden (1880). — A modern investigation of the flora of Saxony, 

 by Prof. Drude. — On the Pycnodontidie, especially the genus 

 Gyrodus, by Prof. Vetter. — The Nudibranchia of the sea, by 

 Herr Blaschka. — On the determination of fixed points of normal 

 mercury thermometers and the measurement of temperatures, by 

 Prof. Neubert. — On various finds in the neighbourhood of 

 Dresden, by Dr. Caro. — Hydroid medusa; or Craspedotes, by 

 Herr Bla.'chka. — Progress of geological researches in North 

 America, by Dr. Geinitz. — On plant-remains from the Tertiary 

 formations of Liebolitz and Putschein, by Herr Engelhardt. 

 — Observations on the growth of the leaf of Victoria re^ia, 

 Lindl., in the Dresden Botanical Gardens in 18S0, by Prof. 

 Drude. — The Slav and German immigration into Saxony, by 

 Prof. Meitzen. — The urn-field of Persia, by Herr Wiechel. 



Archives des Sciences Physiques el Naturelles, No. 3, March 15. 

 Swiss geological review for 1880 (continued) by M. Favre.. — 

 Considerations on the study of phyllotaxy, by M. de CandoUe. 

 —Notice of researches by Drs. Tenchini and Staurenghi, on the 

 anatomy of the human cerebellum. 



Rivista Scientifico-IndustriaU, No. 5, March 15.— On Reese's 

 fusing disk, by Prof. Bombicci. — Volta's pile rendered constant 

 and depolarised, by Count Mocenigo. 



SOCIETIES AND ACADEMIES 

 London 



Royal Society, March 31.— On the coefficients of expansion 

 of the iodide of lead, and of an alloy of iodide of lead with 

 iodide of silver, by G. F. Rodwell, Science Master in Marl- 

 borough College. 



The iodide of lead was examined by the special means 

 described by the author in fora er communications to the 

 Society, and was found to possess three coefficients of expansion. 

 Between o^ and 205° C. the coefficient of cubical expansion for 

 1° C. is •CO007614, increasing to '00008307 between 205° and 



253° c. 



Between 253° and 265° C. the mass expanded very rapidly, 

 with a coefficient nearly eight times greater than the preceding, 

 viz. •0C06378. After the subsidence of this rapid expansion the 

 coefficient became 'oooiSo. The volumes of the iodide between 

 0° and the fu-ing point (383° C.) are given, and are shown in a 

 curve- table. 



Iodide of lead was fused with iodide of silver in such 

 proportions as to form an alloy containing one molecule 

 of each constituent, viz. Pblj, Agl. This contains 66'20 

 per cent, of iodide of lead, and 33*80 per cent, of iodide 

 of silver. The melting-point of the alloy was found to be 350° 

 C, the specific gravity 5'9I2. On heating it was found to 

 expand under a very low coefficiert between c" and 118° C. ; 

 then it neither expanded nor contracted while heated through 6° 

 C. ; at 124" C. it commenced to contract, and underwent 

 between 124° and 139° C. as much contraction as iodide of silver 

 itself ; again it was stationary for 5° C, and at 144° C. it began 

 to expand again, with a much higher coefficient than it possessed 

 between 0° and 118° C. 



The following are some noticeable points about the alloy : — 



1. It possesses similar densities at three different temperatures. 



2. Although it contains only 338 | er cent, of iodide of silver 

 it contracts as much during healing as the iodide of silver itself. 



3. While the iodide of silver commences to contract at 142° 

 C, and terminates at I4S°'S C, the alloy commences to contract 

 iS" C. lower, and terminates its contraction 6°'5 C. lower. 



4. The harsh sounds emitted during the cooling of the alloy, 

 and the tremors simultaneously propagated through its mass, 

 prove that violent molecular agitation is taking place while the 

 iodide of silver is passing from the amorphous plastic condition, 

 into the brittle crystalline condition within the mass of, or 

 surrounded by the molecules of, the iodide of lead. 



5. The fusing point of the alloy is 33° lower than that of the 

 iodide of lead, which constitutes two-ihirds of its weight, and 

 177° lower than that of the iodide of silver, which constitutes 

 one-third of its w eight. 



6. And if this is due to the fact that similar pnrticles of 

 matter attract each other more powerfully than dissim lar, and 

 hence that when the particles of two bodies are mutually diffused 

 the attraction becomes less than that of the molecules "f either 

 one of them singly, and the molecular motion is hence more 

 easily assimilated, the same cause may explain the commence- 

 ment of the phase of contraction on heating the alloy at a tem- 

 perature 18° C. lower than that of the iodide of silver to which 

 it owes this property. 



7. If we compare one of the chlorobromiodides of silver, 

 before described by the author (Proc. Roy. Snc, vol. xxv. 

 p. 29s) with the lead-silver iodide alloy, some curinus anomalies 

 present themselves. The alloy, Agl, AgBr, AgCl (lately also 

 discovered as a mineral), contains 41 '484 per cent, of iodide of 

 silver, and 58'5l6 per cent, of the chloride and bnimide of 

 silver (which from an expansion point of view may he regarded 

 as the same substance, because their co-efficienis are (Tactically 

 the same). But although the mean coefficients of expansion of 

 the chloride and bromide scarcely exceed tho e of the i' dide of 

 lead, and although the chlorobromiodide contains 8 per crnt. more 

 iodide of silver than the lead-silver iodide alloy, the am. unt of 

 contraction by heat of the latter is more than tv\ enty tm es t^reater 

 than that of the former, although we mu^t believe this effect to 

 be solely due in each case to the presence of the iodide ol silver. 



Mathematical Society, April 14. — S. Roberts, F.R.S., 

 president, in the chair. — The chairman firiefly, but feelingly, 

 alluded to the loss the Society had sustaii'ed by the recent death 

 of Mr. T. Cotterill, M.A., formerly Fellow of St. J'hn's Col- 

 lege, Cambridge, who was for many years a menitier of the 

 Council, and had always taken a warm interest in the Society. 



