October 25, 1900] 



NA TURE 



639 



Ebonite showed a slight change of the opposite sign at the 

 fu reheat end, probably due to prolonged inductive action. — New 

 occurrences of corundum in North Carolina, by J. H. Pratt. 

 The niw occurrences are in an amphibole schist and a quartz 

 schist respectively. — Products of the explosion of acetylene, 

 and of mixtures of acetylene and nitrogen, by W. G. Mixter. 

 Acetylene and ammonia yield hydrocyanic acid at a much lower 

 temp2rature than is required to cause nitrogen to combine. It 

 may be that ammonia is the first compound of nitrogen formed 

 in the bomb, but the fact that a little ammonia is found among 

 the products is not conclusive, as that may have resulted from 

 the decomposition of hydrocyanic acid. 



Annalen der Physik, No. 9. — Electric conductivity of pressed 

 powders, by F. Streintz. Fine powders of platinum black, lamp- 

 black and graphite were prepared and subjected to great pres- 

 sure. The resistance of I cubic mm. of platinum black was found 

 to be 0-92 ohm 3 at zero, as againstOT4 for ordinary platinum. The 

 increase of resistance on heating was only half that of platinum. 

 Lampblack showed a corresponding resistance of 40,000 ohms, 

 and a very high negative temperature coefficient, therein resem- 

 bling the electrolytes ; while graphite, with its positive temperature 

 coefficient, ranges itself among the metals. — Resistivity of 

 bismuth in a variable magnetic field, by H. Eichhorn. Bismuth 

 does not instantaneously lose the high resistance it acquires in 

 a strong magnetic field. This is proved by mounting a bismuth 

 coil on a rotating disc so that it traverses a magnetic field once 

 during each revolution, and measuring, by means of contact 

 pieces, the instantaneous resistance at various points of the orbit 

 when at rest and in motion respectively. — Ratio of the thermal 

 and electric conductivities, by E. Griineisen. A very small pro- 

 portion ofarsenic added to copper suffices to reduce the thermal 

 conductivity to one-tenth, and the electric conductivity to one- 

 twelfth of its original value. In iron, the electric conductivity 

 is much more sensitive to impurities than the thermal con- 

 ductivity. — Reflection of kathode rays, by H. Starke. 

 Kathode rays were made to impinge upon a metallic plate 

 enclosed in a cylinder of the same metal, through a small opening 

 in the end of which the rays entered. Another inner cylinder 

 was used to measure the rays reflected by the plate and diffused 

 by the gas, on the principle of Faraday's ice-pail. By putting 

 the plate into two different positions, the diffusion and reflection 

 could be separately estimated. The reflective power of alu- 

 minium was found to be 28-2, and that of copper 45*5. — Me- 

 chanical effect of kathode rays, by H. Starke. The author em- 

 ploys a kathode shaped like a propeller, but fixed. The rays 

 impinge at an angle of 45° upon a thin plate of aluminium sus- 

 pended above the kathode by means of a thin platinum wire. 

 The results are negative so far. — Hardness of metals, by F. 

 Auerbach. The author determines the hardness of metals by 

 his method of finding the greatest pressure between a plate and a 

 lens which the substance will stand without permanent de- 

 formation. Mild steel was found to have a hardness of 361, or 

 that of quartz, hard copper 143 (like apatite), brass 107 (like 

 fluorspar), gold 97, silver 91, aluminium 52, and lead 10. — 

 Thernial conductivity of gases, by P. A. Eckerlein. The con- 

 ductivities of air, hydrogen and carbonic acid are as i : 6 8 : 073, 

 and the temperature coefficients are 0"00362, 0*00422 and 0'00352 

 respectivv ly. 



SOCIETIES AND ACADEMIES. 

 London. 

 Entomological Society, October 3.— Mr. G. H. Verrall, 

 president, in the chair.— Mr. G. C. Champion exhibited speci- 

 mens of Trogoph'oeus anglicanus. Sharp, from Plymouth ; 

 Pachyta sexmaculata, L., from Nethy Bridge, and Anchommus 

 quadripunctatus, De Geer, from Woking. Mr. M. Jacoby 



exhibited an ichneumon from Blandford parasitic on Sirex 



Rhyssa persuasoria, and Col. Yerbury said that he had met with 

 the same species in some numbers in Scotland. One female 

 observed in the act of oviposition had thrust her ovipositor, 

 which is about the consistency of a human hair, through an inch 

 of fir trunk. Col. Yerbury exhibited :—(i) a rare sawfly, 

 Xyphidria cameltu, taken in Scotland this year at Nethy Bridge. 

 The species is mentioned in the old books as extinct in the 

 United Kingdom, and there are no modern specimens in the 

 South Kensington Museum collection. (2) Rare diptera from 

 Scotland including (a) Laphria Jlava, from Nethy Bridge ; (b) 

 C'l-intaesyrphus scaevoides, new to the fauna of Great Britain, 

 NO. 1617, VOL. 62] 



from the Mound Sutherland, where it was common on Um- 

 belliferse under fir trees, one female also being taken on the path 

 up Cairngorm near Glenmore Lodge ; (c) Microdon devius ; and 

 (d) Chilosia chrysocoma at mountain-ash blossom, Nethy 

 Bridge ; (e) Stomphastica Jlava, two males from Golspie, 

 September, 1900.— Mr. H. K. Donisthorpe exhibited (i) a 

 specimem of Drusilla canaliculata, with the dead body of a 

 Myrmica in its mouth, captured at Chiddingfold on July 17 ; (2) 

 Specimens of Myrmedonia collaris and its larva taken in 

 Wicken Fen with M. loevinodis in August, 1900. — The Rev. F. 

 D. Morice exhibited a remarkable hermaphrodite of the bee 

 Podalirius (=AnthopJioia) re/usus, in which the male characters 

 vvere confined to the left side of the head and genitalia, the right 

 side of the thorax and the abdominal segments. The antenna: 

 and hind (pollinigerous) legs were those of a female, and the 

 genitalia half of each sex. — Dr. Chapman exhibited beetles of 

 the genus Orina, some of them alive, and remarked on the fact 

 that while some were viviparous others were oviparous, in the 

 case of the former the larvoe being developed in the ovaries. — 

 Mr. H. J. Elwes exhibited a collection of lepidoptera from 

 Greece, taken this season in conjunction with Miss Fountaine in 

 the Morea, and in the Parnassus region, including Colias hel- 

 dreichi, G. rhamui, var. farinosa. and Lycaena ottoinanus, with 

 a var. of Z. semiargus, probably a distinct species. — Mr. H. H. 

 May exhibited a variety of Strenia clathrata not unlike Syricthtis 

 alveolus on the wing. — Mr. F. Enock exhibited a male bee 

 Sielis atertima, one of the bees parasitic in the nests of Osviia 

 fulviventris, usually considered a rare insect. — Papers were 

 communicated on "Descriptions of new species and a new 

 genus of South American Eumolpidte with remarks on some of 

 the genera," by Mr. M. Jacoby, and on " Lepidoptera Hetero- 

 cera from Northern China, Japan and Corea" (Part iv.), by Mr. 

 J. H. Leech, &c. 



Paris. 

 Academy of Sciences, October 15. — M. Maurice Levy in 

 the chair.— Preparation and properties of the carbides of neo- 

 didymium and praseodidymium, by M. Henri Moissan. The 

 oxides of neo- and praseodidymium heated with carbon in the 

 electric furnace give crystallised carbides of the formula RC.2, 

 like the carbides of cerium and lanthanum. These carbides are 

 decomposed by cold water, giving a mixture of acetylene, ethy- 

 lene and paraffins, the first-named predominating. At 1200° 

 the carbides are superficially attacked by ammonia, some nitride 

 being formed.— Observations of the planet Eros made with the 

 large equatorial of the Observatory of Bordeaux, by MM. G. 

 Rayet and A. Feraud. The planet is of about the ninth mag- 

 nitude, and leaves a clear trace upon the photographic plate. — 

 On the general equation which gives the integral of Jacobi as a 

 particular case, by M. Gruey.— Observations of the Borrelly- 

 Brooks Comet, made with the Brunner equatorial at the 

 Observatory of Lyons, by M. J. Guillaume.— The problem of 

 stationary temperatures, by M. W. Stekloff.— On the explosive 

 mixtures formed by air and by hydrocarbon vapours of the 

 principal organic series, by M. J. Meunier.- On the elimination 

 of the harmonics from alternating currents by the use of con- 

 densers, and on the interest of this elimination from the point of 

 view of security of human life, by M. Georges Claude.— On the 

 accessory reactions of electrolysis, by M. A. Brochet. In the 

 electrolysis of sodium hypochlorite, the loss of hypochlorite in 

 four hours is much greater than that calculated from the current 

 used ; and in the preparation of chlorate yields greater than 

 those calculated are obtained. The author traces these anoma- 

 lous results to the fact that the immediate neighbourhood of 

 the anode is always acid, and hence the hypochlorous acid 

 in that region is transformed spontaneously into chlorate 

 without using electrical energy, even when the bulk of the liquid 

 is alkaline. — On isopyrotritaric acid, a new pyrogenous product 

 from tartaric acid, by M. L. J. Simon. The ferric salt of this 

 acid, the isolation of which was described in an earlier note, is 

 highly characteristic, possessing a deep violet colour in solution. 

 Pyrotritaric acid and similarly constituted furfurane acids do not 

 give this reaction, which is so sensitive that it may be used for 

 the detection of ferric salts and also as an indicator in acidimetry. 

 —On the morphology of the respiratory apparatus of the larva of 

 Brtichtis ornalus, by M. L. G. Seurat. The larva of Bruchits 

 ornatus presents some peculiarities in the morphology of its 

 respiratory apparatus which clearly distinguishes it from the 

 Curculionidrc, the most important being the rounded form of the 

 stigmata, the existence of a prothoracic ring completely uniting 

 the lateral trunks, and of ten transversal latero-ventral anasto- 



