70 



NATURE 



[May 17, 1900 



extended to two years. — Prof. J. Pierpont gives an interesting 

 account of the summer meeting of the Deutsche Mathematiker- 

 Vereinigung held at Munich in September of last year. — Some 

 theorems concerning linear differential equations of the second 

 order is an abstract by Prof. M. Bocher of certain results which he 

 communicated at the February meeting (see ^?//;'<z). — A paper by 

 Dr. M. B. Porter, read at the same meeting, is entitled " A note 

 on the enumeration of the roots of the hypergeometric series 

 between zero and one." It is a continuation of a note published 

 in the May (1897) number of the Bulletin. — Dr. J. Sommer 

 reviews Hilbert's "Grundlagen der Geometric," and Prof. E. O. 

 Lovett does the same for Koenig's " Lemons de Cinematique." — 

 The longer papers read before the Society will, we presume, be 

 printed in the new Transactions, — The notes are very full, and 

 there is a fair list of publications. 



Bulletin de P Acaddmie des Sciences de St. PJtersbourg, vol. vii. 

 No. 3.— On the rotation of Jupiter and his spots, by Th. Bredi- 

 khin. An analysis of the observations made by the author 

 himself at Moscow, and of some later observations at Pulkova. 

 A comparison of the times of rotation of spots situated in the 

 same latitudes shows that some of them are formed in the lower, 

 and some in the higher .strata of Jupiter's atmosphere. Prof. 

 Joukovsky's formula; hold good as a rule ; but a more careful 

 discussion shows that the law of friction must be altered ; the 

 latter is proportional to the square or even to a higher degree of 

 velocity. But it would be extremely difficult to make a theo- 

 retical discussion if the law be altered in this sense. — The 

 scientific results of the Black Sea expedition, by A. Ostrooumov : 

 iii. Fishes of the Sea of Azov. — Materials for the hydrology of 

 the White Sea and the Murman Sea (Arctic Ocean along the 

 Norman coast), by N. Knipovitch : i. Lists of the Observations. 



\^ol. vii. No. 4 — The series of Jean Bernoulli, by N. Sonin. — 

 New researches into the spectrum of )3 LyrEe and m Aquilse, by A. 

 Belopolsky. These new researches were made with the aid of 

 the 30-in. refractor of Pulkova. The spectroscopic velocities of 

 7) Aquilae showed a periodicity very near to the periodicity of 

 the variations of magnitude, i.e. 7 days 4 hours, and it was 

 possible to calculate its orbit. Similarly, as for 5 Cephei, it was 

 proved that the changes of brilliancy in r; Aquilce cannot be ex- 

 plained by eclipses of the star. As regards /8 Lyrae, the former 

 suppositions of the author are now fully confirmed. This star 

 represents a system of two bodies, having at any instant opposite 

 spectroscopic velocities, and one of the two bodies eclipses the 

 other during their revolutions. — Preliminary communication on 

 applications of Rykatschew's method for studying the relations 

 between rainfall and height of water in rivers, by Dr. Harry 

 Gravelius. — The third international balloon ascents of May i, 

 1897, by Ed. Stelling.— Observations of the satellites of Mars 

 with the 30 in. refractor at Pulkova, by F. Renz ; and on the 

 photographs of Mars, by S. Kostinsky. 



Vol. vii. No. 5. — On the changes of pressure under the piston 

 of the air-pump, by Prince Galitzin. Theoretical discussion is 

 compared with direct observation. — Some remarks on the sensi- 

 bility of the eye, by the same author. — Abstract from the yearly 

 report for 1896 of the Central Physical Observatory, by M. 

 Rykatschew. — On the excretory organs of Ascaris viegalocephala, 

 by S. Metalnikoff. — On the routes of the cyclones over Russia 

 in 1890-92, preliminary communication, by P. Rybkin. 



SOCIETIES AND ACADEMIES. 

 London. 

 Physical Society, May 11.— Prof. O. J. Lodge, F.R.S., 

 President, in the chair. — A discussion of Prof. Lodge's paper on 

 the controversy concerning Volta's contact force was commenced 

 by Prof. Armstrong. Prof. Armstrong expressed his indebted- 

 ness to the president for putting forth clearly what we are trying 

 to understand, and said that it was hardly time for chemists to 

 enter the discussion when physicists themselves differed. There 

 has apparently been a change in front since the time when the 

 effect was supposed to be due either to (i) chemical action between 

 the metals, or {2) oxidation. Prof. Lodge's view is intermediate, 

 but approximates to the second. Prof. Armstrong said that 

 from a practical point the existence of the effect was unknown, 

 because sufficient precautions had never been taken to prevent 

 chemical jiction. He urged the continuance of experiments 

 similar to those carried out by Mr. Spiers, and stated that 

 modern ideas of chemistry were favourable to the view which 



NO. 1594, VOL. 62] 



Prof. Lodge had taken up with regard to the Volta effect. 

 — Mr. Glazebrook made some remarks upon the meaning of the 

 term E which occurs in the expression for the Peltier effect at 

 the junction of two metals. If we confine our attention to an 

 infinitesimal cycle at the junction of two metals at slightly 

 different temperatures, we get the equation for the Peltier effect 

 in which E is the potential difference at the point considered. 

 If then, assuming reversibility, we sum up all the infinitesimal 

 cycles round a circuit and get a finite cycle, the E.M.F. of the 

 circuit is a function of the two temperatures between which it is 

 working. Differentiating with respect to temperature the total 

 E.M.F. of the circuit, we get an equation which applies to the 

 circuit as a whole, and in which E is the total E.M.F. round the 

 circuit. Mr. Price asked if any critical experiment could be 

 suggested to settle the question. — Dr. Lehfeldt called attention 

 to some experiments which had been performed to measure the 

 potential difference between an electrolyte and a gas. The 

 electrolytes considered were chiefly aqueous solutions, and the 

 potential differences observed varied largely. The surface 

 tensions of the liquids were measured, and it was shown that the 

 variations in the potential difference were very similar to those 

 in surface tension. This suggests, in the case of electrolytes, true 

 physical surface effects, and not chemical action. — The chairman 

 remarked that Dr. Lehfeldt evidently looked upon the metal- 

 ether boundary as being the effective one. The experimental 

 evidence is not sufficient to say exactly which is the effective 

 contact, but it seems to show that the metal-ether effect is of the 

 same order of magnitude as the oxygen layer effect. According 

 to Helmholtz they ought to be related, and they apparently are. 

 — The chairman then read a paper, by Mr. J. B. Tayler, on the 

 heat of formation of alloys. Experiments have been made 

 upon alloys of lead with tin, bismuth and zinc, and of zinc with 

 tin and mercury. The method employed consisted in dissolving 

 (i) the alloy, and (2) the corresponding mixture of metals in 

 mercury, and measuring the heat of solution in each case. On 

 the assumption that the solutions obtained are identical, the 

 difference between the heat of solution of the mixture and 

 that of the alloy is the heat of formation of the latter. The 

 calorimeter was a thin glass tube silvered on the outside and 

 supported by a stouter tube silvered on the inside. Suitable 

 arrangements were adopted for the introduction of the metals or 

 alloys, which were used in the form of filings. Solution was 

 often complete in less than a minute, and rarely took more than 

 two minutes and a half. The alloys first experimented upon 

 contained their constituents in equivalent proportions, and the 

 heats of formation were found to be small in comparison with 

 those found for brass by Gait and Baker. It was thought that 

 only a small percentage of the atoms present had entered into 

 definite chemical combination, and that more reliable results 

 would be obtained by dissolving a small quantity of one metal 

 in an excess of the other, and calculating from the experimental 

 results the heat of formation of the gramme- molecular weight of 

 compound upon the supposition that the whole of the small 

 quantity of melal had entered into chemical combination by the 

 exercise of its normal valency. Using the numbers so obtained to 

 find, by Kelvin's theory, the potential difference which should exist 

 between the metals concerned when put in contact, results were 

 arrived at which agreed neither with the \'olta effect nor the Peltier 

 effect, but which were considerably nearer the former than the latter. 

 A paper on the want of uniformity in the action of copper-zinc 

 alloys on nitric acid was read by Dr. J. H. Gladstone. ^ Ex- 

 periments have been made by dissolving copper-zinc alloys in 

 nitric acid, following the method of Dr. Gait, and adopting the 

 precautions mentioned by him. The reaction between nitric 

 acid and these metals or alloys is very complicated, and there is 

 a difference between the products in the case of an alloy and in 

 the case of the equivalent mixed metals. The gases evolved be- 

 ing small in the experiments performed, attention was directed 

 to the determination of the substances remaining in solution, i.e. 

 the nitrous acid and ammonia. The alloys gave much more 

 nitrous acid and less ammonia^in fact, two of the alloys em- 

 ployed produced no ammonia. Discrepancies in results may be 

 due to the fact that the zinc and copper in contact form a zinc- 

 copper couple which in the presence of acid sets up a vigorous 

 action and produces a different evolution of heat. Difficulties 

 arise in the investigation because the alloys used may not be 

 definite chemical compounds, but mixtures of two or more alloys 

 with uncombined zinc and copper. The alloy with 38*38 per 

 cent, of copper appears to be fairly uniform. Different ob- 

 servers disagree as to the amount of heat produced by any 



