178 



NATURE 



[December 9, 1909 



demolition of the land by the sea in this part of Holder- 

 ness accounts for this, but it also shows that a long period 

 of time must have elapsed. In all probability these pit- 

 dwellings are among the earliest habitations of Neolithic 

 man which have been found in England. Prof. Boyd 

 Dawkins was present when a fall of cliff had exposed one 

 of these pits on the estate of Colonel Haworth Booth, and 

 verified the fact that the surface soil covering the pit was 

 unbroken, and must have been deposited after the pit had 

 become filled with mud. 



Faraday Society, November 30. — Mr. Tame, Swinburne, 

 F.R.S., president, in the chair. — Dr. H. J. H. Sand : 

 The electroanalytical determination of lead as peroxide. 

 This investigation was carried out with the object of 

 elucidating the cause of the discrepancy between the state- 

 ments of various experimenters regarding the behaviour 

 of an electrolytic lead peroxide deposit on drying at 200°. 

 All authors agree that the peroxide deposit retains water 

 at this temperature, but whereas Hollard and Bertiaux 

 give an analytical factor of 0.853, most other investigators 

 find a factor of approximately 0-864, the theoretical factor 

 being 0-866. Incidentally, the effect of varying conditions 

 on the coherence of the deposit was also studied. It was 

 found that at 200° a lead peroxide precipitate is capable of 

 absorbing moisture from a damp atmosphere, and an 

 increase of as much as 1.7 per cent, of the weight of the 

 deposit has thus been obtained. On heating in a dry atmo- 

 sphere at the same and higher temperatures the peroxide 

 loses its water exceedingly slowly. — A. Jaques : The 

 influence of dissolved gases on the electrode potential in 

 the system of silver — silver acetate, aq. Variable values 

 were found for the E.M.F. of the cell 



Ag I AgCoHgO.,, -rN I NHjNOs.sat. | o'l N.E., 



and the variations were traced to the presence of dissolved 

 air in the silver acetate solution. Measurements were 

 made with saturated and 0-5 N silver acetate solutions 

 saturated with hydrogen, oxygen, nitrogen, and carbon 

 dioxide respectively, and reproducible values were obtained 

 for the solution saturated with hydrogen which agreed with 

 those calculated from the determinations of the E.P. of 

 silver by G. N. Lewis and by Brislee. The values for 

 solutions saturated with carbon dioxide also approximated 

 to_ this. On blowing hydrogen into the solution saturated 

 with carbon dioxide the potential fell about 30 millivolts, 

 then gradually rose to about the normal value. With 

 oxygen and nitrogen equal values were obtained — about 

 20 millivolts below that found with hydrogen. In o.oi N 

 silver acetate saturated with hydrogen the values were not 

 reproducible. Similar measurements with o-i N silver 

 nitrate and 0-5 mol. N lead acetate and lead nitrate showed 

 that in these solutions the electrode potential is practicallv 

 unaffected by the presence of dissolved gases. — .■\. Jaques : 

 Contributions to the study of ionisation in aqueous solu- 

 tions of lead acetate and cadmium acetate. From measure- 

 ments of electrode potentials in solutions of lead and 

 cadmium acetates, and their freezing points, and the solu- 

 bility of silver acetate in them, it "appears that in dilute 

 single solutions ionisation occurs chieflv, though not 

 entirely, according to the scheme 



M(C.,H:,O.0„ :^ MC„H,0„-|-C,n,0' 



mc„h:a =^ m---hC2H30'2, 



where M represents Pb or Cd. Approximate values for the 

 corresponding dissociation constants are calculated. — 

 Prof. F. G. Donnan and Dr. G. D. Hope : The calori- 

 metrical analysis of hydrated salts. The authors point out 

 that the interpretation of the heats of solution of hvdrated 

 and partially dehydrated salt given by Thomsen'in his 

 " Thermochemische Untersuchungen " is in various cases 

 either erroneous or unsatisfactory. It is shown that 

 Thomsen's data for sodium carbonate indicate, when 

 correctly interpreted, the existence of only the hydrates 

 with I, 7, and 10 mols. water per mol. anhydrous salt. 

 The authors' experiments confirm this result. In the case 

 of copper sulphate, neither the experiments of Thomsen 

 nor those of the authors indicate more than the existence 

 of the hydrates Cu.SO,-sH.O and CuSO,.H,0, though the 

 hydrate CuS0,.3H,0 is known to exist. 

 NO. 2093, VOL. 82] 



Linnean Society, December 2. — Dr. D. II. Scott, F.R.S., 

 president, in the chair. — Sir Charles Eliot ; Nudibranchs 

 from the Indian Ocean. — Dr. Georg Ulmer ; Trichoptera 

 von Mr. Hugh Scott auf den Seychellen gesammelt, — 

 Dr. W. H. Dall : Report on the Brachiopoda obtained 

 from the Indian Ocean by the Scalark Expedition, 1905. — 

 Prof. J. S. Gardiner and others : Narrative of the Sealark 

 Expedition, part iii. 



Paris. 



Academy of Sciences. November 29. — M. Bouchard in 

 the chair. — L. Maquenne and M. Demoussy : The 

 blackening of green leaves. The blackening of leaves by 

 the ultra-violet rays is not due to a specific action of this 

 radiation ; it takes place equally under all influences which 

 determine the death of the protoplasm, such as heat, 

 chloroform, or mechanical rubbing. This phenomenon is a 

 consequence of diastatic action, and falls into the same 

 category as the facts observed for the first time by M. 

 Guignard in his researches on the localisation of plant 

 principles. — A. Witz : The regeneration of the exhaust gases 

 from internal-combustion motors. The author suggests 

 that the exhaust gases, taken from the cylinder without 

 cooling, should be passed over a column of incandescent 

 coke. The gas thus produced, containing carbon monoxide, 

 is washed and re-admitted with pure oxygen to the gas- 

 engine cylinder. It is assumed that the price of the oxygen, 

 prepared from liquid air, is now sufficiently low for use 

 in this manner commercially. The utilisation of the heat 

 in the exhaust gases is calculated to give an economy of 

 about 30 per cent. — S. Arloing : Antituberculous vaccina- 

 tion in the ox. An account of the practical results which 

 have been obtained in the direction of obtaining immunity 

 against tuberculosis in cattle in experiments which have 

 been carried on for more than twent}'-five years. — M. 

 Jarry-Desloeres : The period of rotation of Mercury. The 

 surface of Mercury presents a certain number of dark 

 spots, often well defined. The chief difficulty in perceiving 

 these is the bad quality of the telescopic images. The 

 rotation of Mercury from these observations would appear to 

 occupy a long period, and is probably equal to the time of 

 revolution. — Robert Jonckheere : Study of the planet 

 Mars at the Observatory of Hem. Details are given of 

 observations taken between July 16 and November i of 

 this year. — Jean Merlin : Algebraical equations. — M. and 

 Mme. Paul Dienes : Algebraico-Iogarithmic singularities. 

 — Fr^d(^ric Riesz : Linear functional operations. — L. 

 Lichtenstein : The determination of the integrals of the 

 equation 



f!x- cy ex cy 



— H. Pellat : The bifilar pendulum. A supplementary note 

 to a recent paper on this subject dealing with the error 

 introduced by the defective flexibility of the suspending 

 metallic ribbons. — H. Merczyns : Studies on very short 

 electromagnetic waves. Reflection and anomalous dis- 

 persion of liquids. These measurements necessitated the 

 exact determination of the wave-length of the electro- 

 magnetic waves, and the method based on the dimensions 

 of the vibrators not being sufficiently accurate, an inter- 

 ference method was worked out. The dielectric constants 

 with these short waves (4-5 cm.) and the optical refractive 

 indices were compared for several liquids, including 

 glycerin, methyl and amyl alcohols, acetic acid, aniline, and 

 etiiyl ether. — Edm. van Aubel : The production of ozone 

 under the influence of ultra-violet light. Experiments are 

 described proving that ozone is forincd by the rays from 

 a quartz mercury lamp. — Laurent Raybaud : The destruc- 

 tive effect of the solar radiation, .^n account of the action 

 of various radiations on cultures of Phycomyces niteiis. — 

 Georges Meslin : Magnetic dichroism and the orientation 

 of crystals of siderose in the field. — Edmond Bauer and 

 Marcel Moulin : The constant in Stefan's law. A possible 

 .source of error in the determination of this constant by 

 M. F^ry is pointed out, and the constant re-determined. 

 The value 6-oxio-*^ is considered to be correct within 

 I per cent. — E'. Rengade : The theoretical form of the 

 cooling curves of binary mixtures : the case of mixed 

 crystals. — Paul Sacerdote : Changes in the colour of the 

 diamond under the action of various physical agents. The 



