378 



NA TURE 



[August 17, 189^ 



as the temperature increased, the transparency of the film 

 incrcaserl, especially in the more refrangible region. It may lie 

 added that this phenomenon, if found to hold generally, estab- 

 lishes a new correlation between light and electricity, the increase 

 of electrical resistance of a conductor being accompanied by an 

 increase of transparency. 



The alternate current supplied by the Innsbruck Central 

 Station has been utilised by Dr. G. Benischke for the purpose 

 of investigating the dielectric constants of some solids by the 

 method of Gordon as improved by Lecher. This current 

 charged the condenser positively and negatively at equal inter- 

 vals, thus avoiding residual effects of all kinds. In order to 

 obtain greater sensitiveness the alternate current was trans- 

 formed to higher differences of potential by means of an induc- 

 tion coil. It was found that the dielectric constant is independent 

 of the stven^th of the field in the condenser, and hence also 

 that there exists no perceptible conductivity in the dielectric. 

 The constant of paraffin was found to be I '89, of ebonite 2 '03, 

 of sulphur 242, of common glass 4 17 to 4-52, of plate-glass 

 3-8S- 



We have received the supplement to the calendar of the 

 Royal University of Ireland for the year 1893. It contains 

 the papers set at the University's examinations during 1892. 



The report of the fourth meeting of the Australasian .Associa- 

 tion for the Advancement of Science, held at Hobart Town, 

 Tasmania, in January, 1892, has just reached us. It is edited 

 by Mr. A. Morion. 



The Midland Naturalist contains an address delivered by 

 Mr. W. H. Wilkinson, President of the Midland Union of 

 Natural Flisiory Societies, on "The Life-History of the 

 Diamond- B.ack Moth " [Plutelta cruciferarum). We note that 

 at the annual meeting of the Union on July II it was decided to 

 discontinue the publication of the journal. 



Messrs. Crosby Lockwood and Son will shortly publish 

 "The Miner's Handbook," compiled by Prof. Milne, F.R.S., 

 of the Imperial University of Japan. The volume is of especial 

 interest on account of the fact that it is being printed under the 

 author's direction at Tokio. 



A CORRESPONDENT, " H. K. R," writing from Victoria, 

 Australia, with regard to a letter in our issue of March 30, 

 refers us to another and in some respects simpler rule for find- 

 ing the day of the week which corresponds to any given day of 

 the year, to be found in Dr. Charles Hutton's "Mathematical 

 Recreations," published in London in 1803. 



The U.S. Department of Agriculture has just issued a sys- 

 tematic and alphabetic index to new species of North American 

 Phanerogams and Pteridophytes published in 1892, by Miss 

 Josephine A. Clark. The index forms the seventh number of 

 the third volume of contributions from the U.S. National Her- 

 barium. 



Dr. McAlpine has prepared a report for the Victoria De- 

 partment of Agriculture on a poisonous species of Ilomeria 

 found near Melbiurne, causing the death of cattle feeding upon 

 it. The species is Ilomeria coliina, Vent. — var. Rliniata, com- 

 monly known as Cape Tulip. There is evidence that it is fast 

 spreading over the Colony, and strenuous measures will have 

 to be taken to eradicate it. 



We have received the following excerpts from the Proceed- 

 ings of the United States National Museum : Catalogue of the 

 crabs of the family Maudae in the U.S. National Museum ; list 

 of Diatomaceas from a deep-sea dredging in the Atlantic Ocean 

 off Delaware Bay, and scientific results of explorations, by the 

 U.S. Fish Commission steamer Albatross ; also notes on Erian 

 (Devonian) plants from New York and Pennsylvania. 



NO. 1 242, VOL. 48] 



The Memoirs and Proceedings of the Manchester Literary 

 and Philosophical Society (vol. vii. No. 2) contains the second 

 part of Prof. W. C. Williamson's General, Morphological, and 

 Histological Index to his collective memoirs on the Fossil Pl.iirts 

 of the Coal Measures. Prof. Harold B. Dixon, F.R.S., cn- 

 tributes a long paper on the " Rate of Explosions in Gases, ' 

 and in collaboration with Mr. B. Lean, one on the " Lengih 

 of Flame Produced by the Explosion of Gases in Tubes." 



A COPY of Prof. C. V. Riley's presidential address of 

 "Parasitism in Insects," delivered before the Entomological 

 Society of Washington in 1892 has just reached us. It goes 10 

 show that "the parasitic forms and the parasitic habit have 

 appeared late in the history of insect evolution on the globe " 

 A number of papers by Prof. Riley on various entoa.ological 

 subjects have also been received. Among them is one on the 

 habits and natural history of the Ox Bot-fly,- HypoJerma bovis, 

 in the United States. This has hitherto been supposed to lie 

 the common species of both America and Europe, but Prof. 

 Riley finds that the species his not been observed and recorded 

 in North .\merica, hence he considers its presence as merely 

 conjectural. Tne American species is Jlypoderma li'ieala, 

 Villier", and it seem; probable that when the lil'e history af ihe 

 E-aro,iean //. lif'Z'/j has been worked out it will be fuui.d 10 

 coincide with the American Bot-fly as described by Prof. r<iley. 



A NEW mineral of exceptional interest, inasmuch as it con- 

 tains about six and a half per cent, of the extremely rare ele- 

 ment germanium, is described by Prof. Penfield, of the Sbeffield 

 Scientific School, U.S., in the August number of the Ameriian 

 yonnial of Science. Germanium was discovered in the year 

 18S6 by Prof. Winkler in the Freiberg mineral argyrodile, a 

 double i-ulphide of silver ard germanium. The remarkable 

 manner in which the new element was found to currespond wiih 

 the ekasilicon predicted by Prof. Mendeltefl will be still fre.sh 

 in the minds of chemists. Germanium thus belongs to the 

 fourih or tetravalent vertical group of the periodic classification, 

 occupying the space previously vacant between silicon and tin 

 vertically and g.illium and arsenic horizontally. Its atomic 

 weight of 72'3 corresponds aim -st exactly with the ni.mber 

 assigned to the missing ikasilicon by Prof. Mendeleeff. The 

 occurrence of this interesting element appears, as far as the 

 writer can gather, to have been noticed pieviously in only one 

 other mineral specimen besides argyrodite, namely, in euxetiiitt 

 by Prof. Kriis.s, two years after its discovery in the former 

 mineral. Since that time Prof. Winkler has prepared a large 

 number of its compounds and from time to lime described their 

 properties, so that we now possess a considerable amount of 

 information concerning germanium. The third mineral now 

 announced was brought from Bolivia by Mr. Caiifield as a new, 

 rich, and very beautiful silver ore, and submitted to Prof. Pen- 

 field for examination. It has been termed cavfiildile in honour 

 of its finder. The presence of germanium was suspected from 

 its behaviour when heated in closed and open lubes and on 

 charcoal, inasuiuch as it much lesembled the behaviour of 

 argyrodite under similar circumstances. Perhaps the most re- 

 markable characteristic of germanium is that it forms a white 

 sulphide, GeSj. On heating canfieldile in a closed lube the 

 sublimate of sulphide was observed to be white, and, moreover, 

 when the mineral is heated on charcoal a white sublimate of 

 ' oxide and sulphide is produced near the residual be.id of 

 metallic silver, together with a number of milk-whrte semi- 

 transparent fused globules chaiacteristic of germanicoxidc,GeOj. 

 Eventually most of the compounds of germanium were prepared 

 from the mineral and their properties found to correspond io 

 all respects with those described by Prof. Wir.kler. A sulpho- 

 salt soluble in solutions of caustic alkalies like ihe sulphosalts 

 of tin, antimony, and arsenic wasoblaired, and the alkaline so- 



