552 



NATURE 



{April \, 1889 



some analogous sugar. By its twofold decomposition this sugar 

 becomes on the one hand the generator of the cellular tissue, on 

 the other of the starch which is stored up in that tissue. — On the 

 peroxides of cobalt and nickel, and on the volumetric analysis of 

 these metals, by M. Adolphe Carnot. The action of potash 

 combined with that of chlorine, bromine, iodine, or of an alkaline 

 hypochlorite, yields in cobalt and nickel solutions certain black 

 granular precipitates almost identical in appearance. Her- 

 renschmidt, however, has pointed out that the peroxide of cobalt 

 thus obtained has a brown colour, while the peroxide of 

 nickel remains black under the microscope. M. Carnot here 

 describes a series of experiments carried out for the purpose of 

 determining the state of oxidation of the metals in these 

 various precipitates. The general result is that the brown oxide 

 obtained by precipitating cobalt with hydrogen dioxide and 

 caustic potash at the boiling-point has the exact composition of 

 the sesquioxide, C02O3, and that the black oxide of nickel, pre- 

 cipitated by hypochlorite or by bromine and potash, is the sesqui- 

 oxide, NigOg. — On the limits of the errors that may be committed in 

 assaying fine gold, by M. Paul Charpentier. The figures here given 

 are the result of about 3CX) assays executed by the author at the 

 laboratory of the French Mint. — On the initial phase of electro- 

 lysis, by M. PiltschikoiT. A protracted study of the phenomenon 

 of retardation in the electrolytic process leads to the following 

 results. The minimum electromotive force required to at 

 once set up a visible electrolysis does not depend within certain 

 limits on the nature of the salt, nor on the concentration of the 

 solution (gold, zinc, sulphate of zinc ; platinum, copper, sul- 

 phate of copper, nitrate of copper, gold, platinum or silver, 

 &c.). The minimum does not depend perceptibly either on the 

 heat of combination of the two metals, or on their contact electro- 

 motive force ; but it depends essentially on the physical state 

 of the cathode (negative pole), which may modify the resulting 

 figures as much as 20 or even 25 per cent. — On the electric 

 transport of salts in solution, by M. A. Chassy. The special 

 case is here considered of a non-electrolyzed metallic salt, a salt 

 of zinc, for instance, in a mixture of salts of copper and zinc. — 

 On the glycol-ether of chloral, by M. de Forcrand. The author 

 has prepared this compound, 



CCI3 . CH(OH).OC2H40H, 

 in the crystallized state, by combining molecular proportions 

 of chloral and glycol at the ordinary temperature. It is soluble 

 in water, and melts at 42° C, which is also the melting-point 

 of chloral ethylate, according to M. Berthelot. — Determination 

 of the heats of combustion of metaldehyde, erythrite, aud tri- 

 carballylic acid, by M, Louguinine. These experiments have 

 been carried out by means of the calorimetric apparatus under 

 precisely the same conditions as those already published. — Papers 

 were contributed by MM. J. Hericourt and Ch. Richet, on the 

 varying toxic effects of the blood of the dog transfused into the 

 rabbit ; by M. V. Galtier, on the liability of sheep and other 

 animals to contract infectious pneumo-enteritis, hitherto regarded 

 as a disease peculiar to the pig ; by M. Joannes Chatin, on the 

 homologies of the inferior lobes in the brain of fishes ; and by 

 MM. Jules de Guerne and Jules Richard, on the fresh-water 

 fauna of Greenland. 



Berlin. 

 Physical Society, March 8.— Prof, von Helmholtz, President, 

 in the chair. — Dr. Rubens described the experiments which he had 

 made on the selective reflection of light by metals. The method 

 employed was as follows : the light emitted by an incandescent 

 plate of zirconium was concentrated by a lens on to a mirror-surface 

 of the metal under investigation, and the reflected rays were then 

 allowed to fall into a spectroscope with flint-glass prism, whose 

 ocular had been replaced by a bolometer. In this way the 

 intensity of each part of the spectrum could be determined. The 

 next step consisted in removing the mirror and putting the 

 glowing zirconium in the place of the virtual image of the first 

 source of light, in such a way that the rays of light, coming from 

 the point previously occupied by the mirror, pursued the same 

 course as in the first experiment. These rays were then allowed 

 to fall into the spectroscope, and the intensity of each part of the 

 spectrum thus formed by light which had undergone no change 

 by reflection was measured by the bolometer. The intensity 

 ■was determined at fifteen different points in the spectra, extend- 

 ing from near F in the blue into the ultra-red down to the wave- 

 length 2/i. The changes produced in the light by reflection from 

 the metals were represented by curves whose abscissae corre- 

 sponded to wave-lengths while their ordinates corresponded to the 



inteiisities of the several rays after reflection. The results thus 

 obtained showed that silver possesses even for blue rays a very 

 considerable reflexive power, which gradually increases and 

 reaches its maximum in the red, at which maximum the intensity 

 of the reflected light then remains constant even for rays of the 

 greatest wave-length. Gold possesses a much smaller reflexive 

 power for blue and green rays ; the curve then rises very rapidly 

 to a maximum in the yellow and falls again towards the red. 

 Copper reflects the blue and green rays even less than gold does : 

 its reflexive power then increases rapidly into the red, and then 

 somewhat more slowly, until in the ultra-red it reaches a value 

 equal to that for silver. Iron and nickel gave very similar 

 curves, rising at first somewhat rapidly, but subsequently more 

 slowly and continuously into the ultra-red, without however 

 reaching the maximal values observed for copper or silver. On 

 the basis of these experimental values for the reflexive power of 

 the above five metals, the speaker had calculated their coefficients 

 of extinction and refraction for red and blue light, making use of 

 Cauchy's and Beer's formulae. From this it was possible to 

 deduce the dispersive powers of the metals, and to compare their 

 indices of refraction with those which had been experimentally 

 determined by Prof. Kundt : the agreement was in most cases 

 very close. — Prof. Preyer gave an account of some letters of 

 Robert Meyer which are shortly to be published. They were 

 written in the years 1842 and 1844 to his friend Dr. William 

 Griesinger. Prof. Preyer read out several characteristic passages 

 from these letters, in which Meyer states how he arrived at his 

 discovery of the conservation of energy, and from which his firm 

 belief in the correctness of his theory is quite apparent. No less 

 characteristic is the way in which Meyer takes pains to explain 

 his theory to his medical friend, who was but little experienced 

 in physical matters, and to put it before him in a way which he 

 could easily understand. 



BOOKS, PAMPHLETS, and SERIALS RECEIVED. 



A Class-book of Geography (revised edition) : C. B. Clarke (Macmillan). 

 — A Treatise on Chemistry, vol. iii., Part 5: Roscoe and Schorleramer 

 (Macmillan). — The Principles of Empirical or Inductive Logic : J. Venn 

 (Macmillan). — Borneo ; Entdeckungsreisen und Untersuchungen ; Gegen- 

 wartiger Stand der Geologischen Kenntnisse ; Verbreitung der Nutzbaren 

 Mineralien : Dr. T. Posewitz (Berlin, Friedlander).— Tagliche Oscillation des 

 Barometers: J. Hann (Wien).— Journal of Physiology, February (Cam- 

 bridge).— Records of the Geological Survey of India, vol. xxii., Part 1 

 (Calcutta). 



CONTENTS. PAGE 



A " Practical Man " on Electrical Units 529 



The Cephalopoda 530 



Sanitary Science ryi 



Gleanings in Science ' c-ia 



Our Book Shelf:— " ^ 



Porter: " The Gamekeeper's Manual " 534 



Letters to the Editor:— 



The Meteoric Theory of Nebulae, &c. — S. Tolver 



Preston 



535 



The Molecular Formulae of Aluminium Compounds, 



Dr. Sydney Young 536 



Luminous Night-Clouds. — O. Jesse 537 



Zodiacal Light Observations. — W. Donisthorpe . . 537 



Vapour, or Meteoritic Particle. — F. B 537 



The Satellite of Procyon.— H. Sadler 537 



Recent Researches on the Rare Earths as inter- 

 By W. Crookes, 



preted by the Spectroscope. 

 F.R.S 



537 



543 



Notes 



Our Astronomical Column : — 



The Astronomical Society of the Pacific 545 



The late W. E. Tempel 546 



The Companion of Sirius 546 



Comet 1888 ^ (Barnard, 1888 September 2) 546 



Comet 1888/ (Barnard, 1888 October 30) 546 



Saturn's Ring 5^6 



Astronomical Phenomena for the Week 1889 



April 7-13 546 



The Forces of Electric Oscillations treated accord- 

 ing to Maxwell's Theory. III. (Illustrated.) By 



Dr. H. Hertz 547 



Note on the Use of Geissler's Tubes for Detecting 

 Electrical Oscillations. By Dr. E. J. Dragoumis . 548 



Societie:. and Academies 549 



Books, Pamphlets, and Serials Received 552 



