5i8 



NATURE 



\ April 29, 1875 



SCIENTIFIC SERIALS 



Poggendorff'' s Atniaien der Physik und Chemie, 1S75, No. I. 

 This number contains the following papers : — On the electric 

 conducting power of solutions of the chlorides of alkalies and 

 alkaline earths, and of nitric acid, by F. Kohlrausch and O. 

 Grotrian. — On the gliding of electric sparks, by K. Antolik. The 

 author publiihed his first paper on this subject at the beginning 

 of last year, and has since then been gaining much new experi- 

 ence on the subject ; he had observed long ago that if the two 

 discharge balls of a TTolz electric machine are at a certain small 

 distance from each other, the path of the spark is not in a zig-' 

 zag line, but straight, and that the spark is often strongly bent 

 or broken in a certain point, which lies nearer the negative pole. 

 Mr. Aniolik's idea was that negative electricity leaves bodies 

 somewhat slower than positive electricity, and that the bending 

 point in the spark was the place where the two electricities united. 

 He successfully tried to obtain an image of the spark by letting 

 it pass over a blackened glass bulb ; thus he found that the 

 spark glides in three and often five parallel lines. The paper 

 is very elaborate and highly interesting, the author having varied 

 his experiments in all possible ways. — On a universal meteoro- 

 graph for solitary observatories, by E. H. von. Baumhauer. 

 The Dutch Scientific Society of Haarlem offered its gold medal 

 and a purse of 300 florins in January 1S72, for a sufficient means 

 to determine temperature, density, and degree of moisture of the 

 atmosphere at a considerable elevation above the surface of the 

 earth, and in a manner which makes self-registration and con- 

 stant repetition of observations possible. Herr Baumhauer's 

 paper enters into the details of this problem and describes certain 

 instruments which the author devised, and which go far to 

 solve the question at stake, although certain modifications of the 

 Society's demand became necessary, there being a great difference 

 when the term " at a considerable elevation " is applied to a spot 

 which is comparatively easy of access at any time, or when, for 

 instance, it denotes a captive balloon. The author, however, 

 describes instruments which would answer very well in both 

 cases. — Continuation of researches on rod magnetism, by A. L. 

 Holz (see vol. 151, p. 6g of these Annals). — On the measuring 

 of angles by means of the eyepiece micrometer in astronomical 

 telescopes, by Dr. Matern. — On the proportion of specific heats 

 under .constant pressures and in constant volumes, by J. J. 

 Miiller. — On some observations of the spectra of gases, by 

 Eugen Goldstein. The author has made a series of experiments 

 which tend to show that Wullner's idea as to the independence 

 of the gas spectra from differences in the temperature is an 

 erroneous one. They principally consist in intei'poisng a layer of 

 air into the [induction current, which lights up the spectral tubes 

 filled with the rarefied gases, sometimes with a simultaneous 

 insertion of a Leyden jar, and thus forcing the current to pro- 

 duce a spark. Mr. Goldstein then shows that in the whole circle 

 of the current the discharge takes place in the same rhythm, there- 

 fore that the current passes the tube filled with the rarefied gas 

 just as momentarily as any other part of the circle ; from this he 

 concludes that also in the tube the discharge takes place in form 

 of a spark, that therefore the gas ought to show a line spectrum. 

 Now, as this is not the case, and the gas on the contrary shows a 

 band spectrum, the author thinks this a contradiction of Wiill- 

 ner's explanation. — The next paper in the number is by Herr 

 Wiillner himself, and explains the subject very satisfactorily, as 

 he proves that not one of Herr Goldstein's experiments is con- 

 tradictory to his theory of the different spectra of gases ; the 

 form of the electric discharge in the tubes containing the gases is 

 the main point in question, and Herr Wiillner proves this to be 

 in tlie so-called dilated lorm, and not as a spark. — Finally, the 

 number contains a preliminary report by Dr. V. Dvorak, on the 

 velocity of sound travelling in water. 



SOCIETIES AND ACADEMIES 

 London 



Royal Society, April 8. — "Experiments to ascertain the 

 Cause of Stratification in Electrical Discharges in vacuo." By 

 Warren De la Rue, Hugo W. Miiller, and William Spottis- 

 woode. 



Some results obtained in working with a chloride-of-silver 

 battery of 1,080 cells in connection with vacuum-tubes, appear 

 to be of sufficient interest to induce us to communicate them 

 to the Society in anticipation of the more detailed account 



of an investigation which is now being prosecuted, and which it 

 is intended to continue shortly with a battery of 5,000 cells, and 

 possibly with a far greater number. 



The battery used up till now consists of l.oSo cells, each being 

 formed of a glass tube 6 inches (15 '23 centims.) long and \ of 

 an inch (rg centim.) internal diameter; these are closed with 3 

 vulcanised rubber stopper (cork), perforated excentrically to per- 

 mit the insertion of a zinc rod, carefully amalgamated, j\ (0'48 

 centim.) of an inch in diameter and 4 '5 inches (ir43 centims.) 

 long. The other element consists of a flattened silver wire 

 passing by the side of the cork to the bottom of the tube, and 

 covered, at the upper part above the chloride of silver and until 

 it passes the stopper, with thin sheet of gutta-percha for insula- 

 tion, and to protect it from the action of the sulphur in the vul- 



canised corks ; these wires are Vir of ^n ■■^'^h (0'i6 centim. ) broad, 

 and 8 inches (20 '33 centims.) long. In the bottom of the tube 

 is placed 22525 grains (I4'59 grms. ) chloride of silver in 

 powder ; this constitutes the electrolyte ; above the chloride of 

 silver is poured a solution of common salt containing 25 grammes 

 chloride of sodium to I litre (1,752 grains to I gallon) of water, 

 to within about I inch (254 centims.) of the cork. The connec- 

 tion between adjoining cells is made by passing a short piece of 

 indiarubber tube over the zinc rod of one cell, and drawing the 

 silver wire of the next cell through it so as to press against the 

 zinc. The closing of the cells by means of a cork prevents the 

 evaporation of water, and not only avoids this serious incon- 

 venience, but also contributes to the effectiveness of the insula- 

 tion. The tubes are grouped in twenties in a sort of test-tube 

 rack, having four short ebonite feet, and the whole placed in a 

 cabinet 2 feet 7 inches (7S74 centims.) high, 2 feet 7 inches wide, 

 and 2 feet 7 inches deep ; the top being covered with ebonite to 

 facilitate working with the apparatus, which is thus placed on it 

 as an insulated table. 



The electromotive force of the battery, as compared with a 

 Daniell's (gravity) battery, was found to be as l'03 to i,* its 





Lg^^ji^ 



internal resistance 70 ohms per cell ; and it evolved o'2l4 cub. 

 centim. (o'Ol3l cub. inches) mixed gas per minute when passed 

 through a mbcture of I volume of sulphuric acid and 8 volumes 

 of water in a voltameter having a resistance of II ohms. The 

 striking-distance of i,oSo elements between copper wire terminals, 

 one turned to a point, the other to a flat surface, in air, is 

 •5J3 inch ('096 millim.) to ^fj inch (O'l millim.) The greatest 

 distance through which the battery-current would pass con- 

 tinuously /« vacuo was 12 inches (30-48 cent ims. ) between the 

 terminals in a carbonic acid residual vacuum. This battery has 

 been working since the early part of November 1 874, with 

 practically a constant electromotive force. 



Besides 2,000 more cells like those just described, we are 

 putting together 2,000 cells, with the chloride of silver in the 



* Compared with a Daniell's battery, in which the zln( 

 dilute sulphuric acid in a porous cell, its electromotive force is about 3 pe 

 cent, less than tb Daniell. 



