454 



NA rURE 



[March 7, 1895 



The expeiimems appears to prove that wrought iron at a 

 welding temperature possesses the same property of cooling 

 under pressure which was proved by Lord Kelvin to exist in 

 freeiing water, and on which demonstration the generally 

 received theory of regelalion depends. 



The author distinguishes the process of melting together of 

 me:als from that of welding. Either process forms a junction, 

 but the la'ter takes place at a temperature considerably below 

 the melting point. 



The well-known and useful property of welding in iron 

 appears, therefore, to depend, as in the case of regelalion in 

 ice, upon this critical condition, which exists over a limited 

 range of temperature between the molten and the plastic state. 

 " Note on the Spectrum of Argon." By 11. F. Newall. 

 In the course of a spectroscopic investigation in which the 

 author has been for some lime past engaged, a line spectrum, 

 which 50 far as he was able to make out was unknown, 

 had frequently presented itself upon his photographs. It 

 appeared in May and June, 1894, under condition^ which led 

 him to call it, lor the sake of convenience, "the low-pressure 

 spectrum." It now appears that the lines are argon lines. 



The argon o( which the spectrum was observed was obtained 

 from air, from which niirogen was eliminated by parsing electric 

 discharge through it in presence of hydrogen or moisture and 

 acid. Seventy two lines in the author's "low-pressure 

 spectrum" had their wave lengths given in the paper, and side 

 by side were given the measurements of the wave-lengths 

 determined by .Mr. Crookes for the argon lines. 



The agreement of the measurements s hows conclusively that 

 the same spectrum was observed. The agreement of grouping 

 and intensity, also, leaves no doubt as to the identity of the two 

 spectrx 



The experiments were repeated, with slight variations, several 

 times with results which, so far as the spectrum of argon is 

 concerned, were constant. But it was noted that c in inued 

 passage of the discharge appears to result in the attaining o( a 

 certain minimum pressure, after which there is slight and slow 

 rise to a toletably-fised pressure. 



It is interesting to find argon asserting itself, unsolicited, in 

 quite new circumstances, and under conditions which practically 

 constitute one more mode of separating argon Irom niirogen — 

 namely, the getting lid of nitrogen by passing electric dis- 

 charge through it in the presence of hydrogen or moisture 

 and acid. 



February 28.—" The Effect of Environment on the Develop- 

 ment of Echinoderm Laivae: an Experimental Inquiry into 

 the Causes of Vaiiation." By M. M. Vernon (from the 

 Zoological Station, Naples). 



Tht: conditions of environment under which an organism 

 develops are known to be of considerable iulluence in the pro- 

 duction of variations. It was thought to he of interest to 

 determine by exact measurement the trfifects which such slight 

 change- in the environmental conditions as might occur 

 naturally would produce in ihegrowtn of some organisms. The 

 animal chosen was the larva or pluteus ol the sea-urchin 

 Strrni^yloctntrolus Itvidut. These larvje develop readily from 

 arlihcul leriilisations, and they can, moreover, be o named at 

 all lime? of ihe year, irrespective of season. In all 10,000 

 larvx were measured. 



'1 he effects 01 temperature on development were first s'udied. 

 It was found that if the ova were pliced in wa era' about 8° or 

 25' C. for an hour, or even for a minute, at the time of im- 

 P'Cgnaiion, the resulting larva; after ti.;nt days development 

 Wire, on an average, 46 percent, smaller than those impregnated 

 at from 17° to 22', though all the su! sequent condiii.ms of 

 development wne identical. 11 kept at the almormal tem|icra- 

 lure for only ten seconds during impregnati .n, the resulting 

 larvx *crc only I 7 per cent, smaller. 



The timcol the year when the artificial fertilisations are pre- 

 pared h.is a very marked inlliiencc on the size of the larvae. 

 1 hus, tho e ob ained in the middle ol August ate about 20 per 

 cei t. »m Her than ih.se nl>iaincd in April, May, and October, 

 whil t ihoic olita.ned in June and July arc interinciliate in 

 lize. 



The iialinity of the water has also a great influence on the 

 developmrnl. 



The effrciii which the variou* colours of the spectrum have 

 upon ihe iltvelopmcnt were al«) deietmined, ihoi'gh these are 

 Dot condition" ol envi.oimciil which occur In naure. The 

 development of the larva: seem* to be but little aflccled if it is 



NO. 1323, VOL. 51I 



carried out in absolute darkness, the size only being diminished 

 by I 3 percent. Larvae grown in semi darkness are apparently 

 25 percent, larger than the normal. 



The body-length of the Inrva: appears to be uninfluenced by 

 the number of larvx developing together in a given volume of 

 water, if it be kept below 30,000 per litre. The arm-lenglhs 

 are, on the other hand, considerably affected. 



Certain products of metaholism exert a favourable influence 

 on the developments of the larvje, and not, as would be 

 naturally expeced, a harmful one. 



.\s the number ol measurements made was so large, it was 

 thought to be ol interest to subject them to statistical examin- 

 ation. It was found that with the body-length and oral arm- 

 length measurements the deviations from the average occurred 

 with a frequency indicated by the theoretical law of etior. The 

 measurements of the ahoral arm-length did not agree so well, 

 possibly owing to dimorphism. 



Physical Society, February 22.— Captain Abney, F. R.S., 

 President, in the chnir. — \n abstract of Mr. G. H. Bryan's 

 paper, on the mechanical analogue of theimal equilibrium 

 between bodies in con'act, was read by Mr. EMer. After com- 

 menting on the difficulty in applying the kinetic theory of gases 

 to the case of two substances in contact which do not mix, the 

 author goes on to describe a system by which the phenomena 

 of thermal equilibiium unaccompanied by diffusion can be ex- 

 plained. The two substances are represented by two sets of 

 molecules designated by 1' and Q. Two parallel planes A aiid 

 B, at a small disiance apart, are imagined to divide space in 

 three parts. Plane A ('o the left of B) is supposed to be 

 permeable to the P molecules, but to repel the Q molecules, 

 whilst B is permeable to the Q set of molecules, and repels the 

 P set. The spaces to the left ol A and to the right of B are 

 thus entirely occupied by the P and (1 molecules respectively. 

 Between the planes both P and (> molecules exist, and there- 

 fore have oppori unities of colliding with one another and 

 transferring energy from one gas to the other. Using 

 generalised dordinates, it is shown by Bolt^mann's method 

 that when equilibrium is attained the mean kinetic energies ol 

 translation of the two kinds of molecules are equal, just as ioi 

 the case of molecules which mix. Instead of assuming thtj 

 planes .\ and V, to repel the Q and P molecules respectively, 

 the P molecules may be assumed to be positively electiified, an<i 

 the (1 ones negatively electrified, whilst the planes A and I 

 are maintained at a constant difference of potential. Thi 

 difference of potential thus assumed is analogous to " contac 

 E.M.F." whose existence is proved by experiment. Thij 

 communication concludes with a development of Prof. Bolti j 

 mann'spaper on the application of the deierminanlal relatioi' 

 to the kinetic theory of polyatomic gases, read before thi: 

 British Association at Oxford. Dr. Stoney thought the argu 

 mcnts were based on actions depending on the distances of th' 

 molecules, an 1 the supposiiion that they were rigid. In hi 



o|iini(m eve 



nts occur in nature which are not represented b;' 



his simple theory, and great reservation should be shown 11! 

 accepting dynamical pr .blems which leave out of accoun 

 actions occurring between matter and the ether. In natur: 

 nothing was large and nothing was small except relatively 

 Even molecules might possess infinite detail of structure 

 Their inter.action with the ether must be considereil in an, 

 complete theory. — Mr. G. U. Yule's paper on a new harmoni 

 analyser, and one by Mr. H. N. Allen, on the elect rom.igneti 

 ficlil, were postponed. . 



Chemical Society, February 21.— Dr. Armstrong, Pres 

 dent, in the chair.— I'he following papers were read :— TbI 

 electromotive force of an iodine cell, by A. P. Laurie. Ih 

 E M.K. of a cell consisting of a zinc and pl.itinu o jilale ml 

 mcrscd in iodine dissolv.d in potassium iodi.lc solution is con 

 Slant, but is the smaller as the iodine solution is ihe moi| 

 dilut- ; Ihe.fTecl of varying the con-stituents of the cell on tlij 

 I' M V. has been investigated. —Ctmiribuiions to the chemlJli 

 otccilulose. by C. F. Cross, E.J. Hevan, and C. Beadle. TJ 

 meltii.gpoinis of mixtures, by II. Crompton an.l Miss M. /I 

 Whitcicy. When a solution deposits ihe pure solvent on coo 



ing, the relation log s= ^f^^ . ^- ~ ^r h"''''* ! ' ^^ "-e numb. 



ol molecules of solvent per molecule of solution, p is I'le njo' 

 cular latent heal of fusion of the solvent, and 1 tind 1 t 

 melting-poinis of ihe solv.nt and the solution rcspectively.--ll 

 volumetiic determination ol manganese, by J. Reddrop and I 



