May 25. 1893J 



NATURE 



79 



tures ranging froiii 10° to 40° C, and with varying current 

 densities. The method adopted to determine the difference of 

 potential consists in forming, with the two plates which are 

 being experimented on, a condenser having its plates joined by 

 a wire in which an opposing electromotive force could be pro- 

 duced. The conclusions the author arrives at are, that the 

 difference of potential at the point of contact of two electro- 

 lylically deposited layers of the same metal is independent of 

 the density of the current, and of the temperature and com- 

 position of the solution used in forming the deposit. He also 

 finds that two deposits prepared at different times are identical, 

 and give no contact difference of potential even when as much 

 as a month elapses between their preparation. 



An improved apparatus for exhibiting the phenomena of 

 gaseous diffusion is described by Prof V. Dvorak in the Zsit- 

 schrijt fur Pkysikalisclieii Unterricht. A porous pot such as is 

 used for galvanic batteries, but in a fresh and clean condition, is 

 well closed by a greased cork through which pass a bent glass 

 rod and a glass tube. The tube is attached to a narrow india- 

 rubber tube leading to a horizontal capillary glass tube ending 

 in a small cup. The capillary tube contains a drop of alcohol 

 which serves as an indicator. The earthenware pot is placed in 

 an inverted position, the glass rod serving as a handle. A tray 

 of sulphuric acid containing pieces of zinc is placed under an in- 

 verted beaker, which collects the hydrogen evolved and is 

 then slipped over the porous pot. The gas, entering the pot by 

 diffusion more rapidly than the air leaves it, drives the drop of 

 alcohol quickly outward. A similar effect is produced by coal- 

 gas, and the opposite effect by carbonic acid or ether. This may 

 also be strikingly shown by lightly breathing into the beaker and 

 applying it to the porous pot, when the displacement of the drop 

 will indicates the presence of the heavier gas in the breath. 



It is a common belief in India that, if a cobra is killed, and 

 the remains are left in a bungalow, others of the species will be 

 auracted to the spot. A correspondent of the Pioneer Mail 

 records an incident which appears to indicate, as he says, that 

 there is some truth in this theory. About nine months ago Col. 

 Ilderton killed a very large cobra in the compound of his bunga- 

 low at Dinapore, and had its skin stuffed and set up by a native 

 mochee. Since then the compound has been infested with these 

 snakes, and no less than eight full-grown cobras, measuring 

 from 4 ft. Sin. to 5 ft. 4 in., have been killed there; one of 

 which was sittingup, with iis hood extended, contemplating the 

 house where the remains of its preserved friend were. It is a 

 curious fact that every snake when found was making in the 

 direction of the bungalow, and most of them showed fight when 

 tackled. The last two were within a few feet of each other, 

 when Col. Ilderton killed them with a stick, and were advancing 

 up the carriage drive together. No cobras have been seen in 

 other parts of the station. 



Mr. Hope Hunter, writing in the Journal of the Royal 

 Agricullural and Commercial Soeie/y of British Guiana on gold 

 in that colony, says that the explorer h.as no reason to penetrate 

 further than two hundred miles inland for the discovery of new 

 and extensive gold fields, but that, if he desired to extend 

 research further, the debatable Kind between the colony and 

 the Brazilian possessions in the south would offer a favourable 

 field for exploration. Mr. Hunter has been made acquainted 

 with some particulars of an expedition composed of a parly of 

 Americans to that part some years ago. They discovered abun- 

 dant evidence of the country being rich in precious metals, but 

 the hostility of the Indians, culminating in the massacre of 

 nearly the entire party, prematurely terminated their investiga- 

 tions, the few survivors making their escape with much difficulty. 

 Mr. Hunter says that this portion of the South American 

 continent is inhabited by various Indian tribes who are believed 



NO. 1230, VOL. 48] 



to practise cannibalism, and that one tribe, the Pianoghottos, 

 on the confines of British Guiana, are well known for their 

 inveterate hostility to strangers, many instances having been 

 recorded of their having repulsed and murdered boats' crews 

 penetrating to their country from the Brazilian side. 



Several parcels of land and fresh-water moUusks collected 

 by Prof. Jose N. Rovirosa, mainly in the State of Tabasco, 

 Mexico, were sent last summer to the Academy of Natural 

 Sciences, Philadelphia. As some of them are of considerable 

 interest, a list has been prepared by Mr. H. A. Pilsbry, and is 

 printed in the latest instalment (Part III.) of the Academy's 

 "Proceedings" for 1892. The list is illustrated with several 

 figures brought together on a single plate. 



The bulk of line gloves produced in Russia are made, it 

 seems, from foal skins. So says the U.S. Consul-general at 

 St. Petersburg in a recent report on the subject. Very little is 

 done in Russia, he says, in the manufacture of gloves from 

 sheep, goat, or kid skins. Much hand-labour is needed to pre- 

 pare foal skins for gloves, and it is doubtful whether they could 

 be profitably used in countries where hand labour is dear. 

 When well dressed they are very durable, and at the same time 

 delicate, and have a great advantage in taking well all sorts of 

 dyes. 



The report of the United States Commissioner of Fish and 

 Fisheries for the fiscal year ending June 30, 1889, has just been 

 issued. Among the appendices is an elaborate and valuable re- 

 ])ort on the fisheries of the Pacific coast of the United States, by 

 J. W.Collins. The scope of this report is limited to a considera- 

 tion of such fisheries as are prosecuted in or from the region 

 embraced between the southern extremity of California and the 

 north-western limit of Washington. Incidentally, a somewhat 

 extended reference has been made to certain phases of fishery in 

 Alaska, in explanation of industries which are controlled by 

 capitalists of San Francisco, or elsewhere, and constitute a part of 

 the fishing interests of the region specially treated of in the 

 report. 



The Journal of Geology, which is being issued from the 

 University Press of Chicago, promises to be a periodical of 

 much interest to geologists. Two numbers have been pub- 

 lished, and among the contents are papers on the preCambrian 

 rocks of the British Islands, by Sir Archibald Geikie ; geology 

 as a part of a college curriculum, by H. S. Williams ; an his- 

 torical sketch of the Lake Superior region to Cambrian time, 

 by C. R. van Hise ; the Glacial succession in Ohio, by F. 

 Leverett ; traces of Glacial man in Ohio, by W. H. Holmes; 

 and the volcanic rocks of the Andes, by J. P. Iddings. 



Messrs. Gauthier-Villars et Fils have added to their 

 " Encyclopedic Scientifique des Aide-Meojoire " a volume en- 

 titled, " Traite Pratique de Calorimetrie Chimique," by M. 

 Berthelot, secretary of the Academy of Sciences. In the same 

 scries have been published " L'.\rt de Chiffrer et Dechiffrer les 

 Depeches Secretes," by the Marquis de Viaris ; " Unites et 

 I'Ualons," by C. E. Guillaume ; and "Principesde la Machine 

 a Vapeur," by E. Widmann. 



A VOLtJME containing an excellent account of "The Story 

 of the Atlantic Telegraph," by Henry M. Field, has been 

 issued by Messrs. Gay ar;d Bird. The " story " is one of pro- 

 found interest, and the author tells it vigorously and clearly. 

 He is a brother of the late Cyrus W. Field, and has therefore 

 had access to many new and important sources of information. 

 He does full justice to the part played by his brother in the great 

 enterprise, but does not underrate the services rendered by " the 

 science and seamanship, the capital and the undaunted courage, 

 of ICngland." 



