25« 



NATURE 



[Decemb! 



In the AiU dei Lined, x' 



describes r- •• <\i\,.,^ v. ,ii 



classical ' 



• tun 



1.=; " 



Ifyl I 



)re»ence <rf 

 -1 r.nd 



\;iiiinn, riinl I !:■ r; ;iL;.'iin 



li. 



Sir nKORcn CiRrrNiiin., uiiiiiu^ in 77/. .. jnutnal 



;;i., .), i|.\'ln|i> till- I'viiit iii.|;iiii' d !■'. 



II) wliiili llii- null til i;il (if ri 1: 



geneoiis spherical segment (ct,'. a Hat Uns) at n 



can be made to depend on cllifitic intci^i als, '! ! 



depends on the method of dissection empliMd ; iti 



the segment must be supposed cut into slii . s p' ip 



to the line joining the centre to th'- ])nint ai whirh tli- 



potential is required. 



According to a paper by Messrs. l\in.i-hii.-i atul liliiiuih. 

 in vol. iii. of the Memoirs of the Si i. ik c an! ' 

 Collogo of the University of Kyoto, tli'- iuni 

 from a metal filament whi-n heated above 2400" ahsokii'- 

 ceases to be represuiibd liy Prof. Richardson's equation 

 C=A^d.e~*^*, where C is the value of the saturation 

 current, the absolute temperature, and A and 6 constants 

 depending on the nature of the metal. They put this 

 down to the fact that the equation is deduced on the 

 assumption that the whole of the saturation current is 

 carried by the ions emitted by the heated filament. At the 

 high temperatures they attained they consider the kinetic 

 ertergy of the moving electrons sufficient to enable them 

 to ionise the gas molecules with which they come into 

 contact. The magnitude of the current thus produced 

 appears to be roughly half that of the total current 

 observed. 



The Verhanilungen der Deutschcn Physikalischen Gssell- 

 schaft for November 15 contains a short report laid before 

 the meeting of the Naturforscher und Aerzte at Karlsruhe 

 by Drs. Scheel and Heuse, on the measurements of the 

 specific heat of air at ordinary and at very low tempera- 

 tures recently made at the Reichsanstalt. The method 

 used was that of " continuous flow," the air passing 

 through a vacuum-protected tube in which it was heated 

 by a wire carrying an electric current, its temperature 

 on entering and in leaving being measured by platinum 

 thermometers. The results for the specific heat are as 

 follows : — at 20° C, 0241 ; at_ —78° C, 0243 ; at 

 — 183° C, 0-252. There is, therefore, a distinct increase 

 of the specific heat as the temperature decreases. The 

 result at 20° C. agrees to within i part in 1000 with 

 that obtained by the same method by Dr. Swann, and 

 published in the Proceedings of the Royal Society of 

 London in 1909. The complete account of the work of 

 Drs. Scheel and Heuse is to appear in the Annalen der 

 Physik. 



Thb November issue of the Chemical Society's Journal 

 contains a paper by Prof. G. G. Henderson and Mr. I. M. 

 Heilbron on the constitution of camphene. It is now 

 generally recognised that the formula I., 



CH^-CMe— CH 



I 

 CMca 



CHyCH— CH 

 1. Bornylen*. 



CH.CMe- 



I 

 CMe, 



/ 



C = CHs 



-/ 



CH.CH 



II. Campliene. 



originally proposed by Bredt, is in reality that of the closely 

 related bornylene, as is shown by its preparation from 



NO. 2199, VOL. 88] 



til. 



.\ 



l.a . .. 



("li phrnylhydrazone of 



;ii . ; property that the 



a-iMiiii. HI 1: rm, melting at 56", 



... 1 en" infn »lif. other 



thu« 



..,. ,..,.,...,.,,,.., .. ...lie of 

 ;4h-mclting a-form, whilst 



r.-M-\-^i;.i!,-;ui..:i m-w. .,ii,i..i. '■■ ' :.,:.,.< -, '-rtre of 



sulphur (lii)xi(ii- ^avi- th. This 



piculiaritv of the isomeri'-m i'' onviousiy < udih-i tt-u with a 

 vcrv small difference in the energy-content (and therefore 

 in the stability) of the two forms. This factor is usually 

 overbalanced by a marked difference in the solubility of 

 the two forms, a difference which som' " ' .ours either 



the one or the othf>r form according • .vent from 



which th<» matfi-ial llisrd. But In th- case under 



consideration tlv '. -J solul>ility almost disappears 



on account of the fact that the two forms are isomorphous. 

 Their interconversion can therefore take place with peculiar 

 facility, and in the case of the solids may be brought about 

 by gaseous acids and alkalis without producing any altera- 

 tion in the appearance of the crystals. 



Engineering for December 15 contains an account of 

 some valuable experiments on the strength of thick hollow 

 cylinders under internal pressure, carried out by Messrs. 

 Gilbert Cook and .\ndre\v Robertson at the University of 

 Manchester. The object of the experiments was to test 

 the various theories for the manner of failure, and cylinders 

 both of cast iron and of mild steel were tested. In the 

 case of cast iron, elastic limit and rupture are practically 

 coincident; the results periments show that the 



failure is determined - the maximum principal 



stress, and Lamp's formula, 



may be used directly. In this formula f '- ''" " *' 

 failure in simple tension, and k is the inii : th< 



1-1 the mild-steel cylinders testoa. ,11:1. ai yield 

 iien the pressure was about 20 per cent, in 

 excess ut tliat required by the shear-stress theory (Guest'lj 

 law) ; the pressure may be calculated very nearly by tM 

 equation 



Tests were also made on the ultimate strength of mild-stee 

 cylinders. The results may be denoted empirically by th« 

 same formula that applies: to cast iron. 



We have received froi la;; • - \\ooI!- y. Sor.s ar 



Co., Ltd., of Victoria BnUg:, .Manchester, a copy of thei 

 " Scientists' Reference Book and Diary for 1912." Il 

 addition to a conveniently arranged diary, in which eacti 

 week of the year is given a page, a reference book con- 

 taining useful information as to important facts and 

 constants continually required by workers in science is 

 provided. The tables and other data have been carefully 

 revised, and will prove of great service. The price of the 

 publication is is. 6d. 



