Jan. 8, 1880 



NATURE 



243 



jection upon the screen ; and M. Guebhard awakened a lively 

 interest when he proceeded to show that such films, especially 

 the fleeting films condensed from the breath, may exhibit phonei- 

 doscopic properties. The various vowels being pronounced so 

 that the breath impinges on the surface of the cooled mercury, 

 rings are obtained having certain forms more or less strongly 

 characteristic of their different qualities of tone. 



The influence of temperature on tuning-forks (which are now 

 such valuable aids to research), has been lately investigated by 

 Herr Kayser (Ami. de Phys. No. 11), and by the method of ob- 

 serving the alteration of the difference of phase of two forks 

 with the temperature. The forks were furnished with mirrors 

 and the Lissajous figures observed with a telescope. These re- 

 sults were arrived at : I. The vibration number of a tuning-fork 

 is, between 0° and 30 , a linear function of the temperature. 2. 

 The influence of temperature is greater, the higher the tone of 

 the fork, and with similarly arranged forks, the variation of the 

 vibration number is about proportional to the square rcot of that 

 number. 3. With moderate variations of temperature, such as 

 occur in a room, the temperature affects the vibration number in 

 the second place of decimals. 4. The coefficient of elasticityof 

 steel increases between o° and 30" w-ith the temperature. 



OcACH proved, a few years since, that alloys of the metals 

 proper, such as lead and tin, potassium and sodium, and sodium 

 amalgam, conduct a current, without being decomposed. Herr 

 Elsiisserhas recently (Ann. der Phys. No. 11) experimented with 

 combinations of metals with the half-metallic elements antimony 

 and bismuth, passing a current through the fused alloy in a glass 

 tube with electrodes of gas carbon. There was here also no 

 decomposition. The author notes that the transition from these 

 compound conductors of the first class to the electrolytes is no 

 sudden one. Between the two groups are substances, which at 

 a low temperature conduct without decomposition, but at a highi 

 one, and even partly before they melt, are electrolysed, e.g. copper 

 and silver sulphides, and the sulphides of lead, nickel, iron, 

 bismuth, tin, and antimony. To this middle class, also, may be 

 added a number of compounds, which have not hitherto been elec- 

 trolysed, probably because they are so difficult to fuse (such as the 

 oxides of tin, iron, and chromium) ; the electrolytes proper do not 

 conduct without being electroiysed; and to this class belong espe- 

 cially the haloid compounds of the metals, v, Inch are not decom- 

 posed in the solid state because they are insulators; whenever they 

 begin to conduct, being fused, they are decomposed. Lastly 

 there is a fourth class of compounds, which in general do not 

 conduct, either with or without decomposition. 



An experimental determination of the indices of refrac- 

 tion of some liquefied gases has betn lately made by Herr 

 Bleekrode (Ann. der Phys. No. 11). He used the method 

 of Faraday's tubes, but observed the liquefied gas with 

 a microscope in a small vessel with plane parallel sides 

 having mirror plates. Only cyanogen, carbonic acid, and 

 ammonia, were thus successfully examined, and the average 

 numbers obtained for these were, severally i'320, 1 163, and I '314. 

 The method is also useful for compounds which arc liquid at 

 ordinary temperature, but difficult to examine on account of their 

 inflammability. Thus, the author applied it to zinc-ethyl, 

 obtaining the number 1 '489. A propos of the index of carbonic 

 acid, Herr Bleekrode has some interesting remarks on liquid 

 inclosures'in certain minerals. In another paper he hopes shortly 

 to give the indices of most of the other liquefied gases, his ex- 

 periments on which were, in part, accomplished with Cailletet's 

 compression apparatus. 



The somewhat doubtful name Audiphone has been given by 

 Mr. Rhodes of Chicago to an instrument to improve the hearing 

 powers of the partially deaf. We understand that it consists es- 

 sentially of a flat flexible disk of resonant metal furn^hed with a 

 handle, like a palm leaf fan and capable of being adjusted in 

 curvature by means of a cord and a tightening clamp. The 

 edge of the disk is to be pressed against the upper front teeth 

 while its concave surface is presented towards the speaker to re- 

 ceive the sounds. The vibrations thus taken up by the disk are 

 transmitted through the teeth and bones of the skull to the audi- 

 tory nerves. This would appear to be a more practical instru- 

 ment than the megaphone of Mr. Edison, of which nothing has 

 been heard of late, or the apparatus recently explained by M. 

 Paul Bert to the Academic da Sciences. Mr. J. .Samuelson of 

 Liverpool, exhibited the Audiphone at the late soiree of the 



! ! ill. 



Prof. C. S. Hastings of the Johns Hopkins University has 

 contributed to the current number of Silliman's Journal an im- 

 portant paper on "Triple Objectives with Complete Colour 

 Correction." He controverts the opinion of Prof. Harkness 

 expressed in a preceding number of the journal that the focal 

 plane of a system of lenses does not correspond to the minimum 

 focal distance. 



It is stated that a new photographic process has just been 

 discovered in Japan by an inventor whose name is not given. 

 One of the substances employed in the manufacture of Japanese 

 lacquer has the property of becoming almost as hard as stone 

 under the action of light. A slab covered with this material 

 and duly exposed behind a photographic "negative" for some 

 twelve hours, was afterwards scraped, and rubbed with spatula 

 and brush, leaving the hardened portions raised in low relief, 

 and capable of being used as a block for printing. 



Our contemporary, the Electrician, announces the startling 

 discovery of an electric divining-rod, "whereby paying deposits 

 of gold, silver, and copper can be positively indicated, and their 

 exact location pointed out." This "discovery" is of course a trans- 

 Atlantic one, but, "strange to say, it does not emanate this time 

 from Menlo Park, though Mr. Edison may of course have pre- 

 invented it many years ago ! " 



In the Institutes 0/ Akbar, whose reign over a considerable 

 part of India extended from 1560 to 1600, are found the fol- 

 lowing directions for the artificial freezing of water. Into two 

 parts of water is thrown one part of dry powdered nitre. In this 

 mixture a small stoppered silvered jug containing pure water is 

 stirred about briskly for a quarter of an hour, when its contents 

 will be found to be wholly or partially frozen. 



SCIENTIFIC SERIALS 



Journal of the Royal Microscopical Society, vol. ii. Nos. 7 and la, 

 contains. : — Transactions of the Society. — W. II. Gilburt, On 

 the morphology of vegetable tissues (Plates 22 and 23). — J. Beck, 

 On the structure of the scale of a species of the genus Mormo. — 

 Prof. E. Abbe, On new methods for improving spherical correc- 

 tion, applied to the construction of wide-angled object-glasses. — 

 II. E. Forrest, On the anatomy of Lcptodora hyalina (Plates 24 

 and 25). — Dr. H. Stolterfoth, On a new species of Eucampia. — 

 John Mnyall, jun., On an immersion stage illuminator, and on 

 aperture measurements of immersion objectives expressed as 

 "numerical aperture." — J. W. Stephenson, On a table of nume- 

 rical apertures showing the equivalent angles of aperture of dry, 

 water immersion, and homogeneous immersion objectives, with 

 their respective resolving powers, taking the wave-length of line 

 E as the basis ; a = n sin. w, n = refractive index, and w — \ 

 angle of aperture. — The record of current researches relating to 

 zoology, botany, and microscopy. — Bibliography. — Proceedings 

 of the Society.— The editor announces that the Society has 

 obtained the assistance of Mr. T. Jeffery Parker, Mr. A. W. 

 Bennett, and Prof. F. Jeffrey Bell in the production of the 

 journal. — No. 7<z is a supplementary number containing the index 

 to vol. ii., List of Fellows of the Society, &c. 



Proceedings of the Boston Society 0/ Natural History, vol. xz. 

 part 2, November, 1S7S, to April, 1S79. — Dr. II. A. Ilagen, 

 Larva' of insects discharged through the urethra, and On bird;; 

 Storming' after white ants. — Dr. S. Kneeland, Traces of the 

 Mediterranean nations in the Northern Ocean. — Dr. II. A. 

 Hagen, Remarks on white ants. — President Bouve, Reniarl s on 

 the death of Dr. J. B. S. Jackson.— rrof. N. S. Shaler, Evi- 

 dences of a gradual passage from sedimentary to volcanic rocks 

 in the Brighton district. — Dr. H. A. Ilagen, Flies from a petro- 

 leum lake.— W. O. Crosby, Occurrence of fossiliferous boulders 

 in the drift of Truro, Cape Cod. — Dr. S. Hunt, On the pre- 

 Cambrian rocks of Great Britain. — W. II. Patton, Synop.-is of 

 the New England species of Colletes. — J. S. Kingsley, Notes of 

 North American Decapoda. — W. P. Crosby, A possible origin 

 ofpetro-silicious rocks.— B. D. Halsted, The American species 

 of Characeiv. The author enumerates eight species of Nuella, 

 one of Tolypella, and nine of Chara, one of which, C.robbinsii, 

 from Rhode Island, is described as new. — Dr. C. S. Minot, 

 Growth as a function of cells, and On certain laws of histological 

 differentiation.— Rev. G. F. Wright, The kames and moraines 

 of New England.— Mr. W. Upham, Glacial drift of Boston and 



