NATURE 



[May II, 1893 



220,000 ounces of silver, and between 600 and 800 tons of lead 

 per week. Speaking of the products of the refinery, the authors 

 said they were thus disposed of: — The pure silver was sold in 

 the colonies by tender at stated intervals, in parcels of between 

 100,000 ounces and 150,000 ounces, and was purchased by the 

 banks usually at a price somewhat above the price current in 

 London. The soft lead was shipped either to England or to 

 China ; the latter country was becoming gradually a larger 

 buyer of the company's lead. The matte and other compound 

 products were shipped to England. The small amount of gold 

 in the ore was recovered in the refinery. It amounted to about 

 3'4 dwt. per ton of bullion. 



Mr. C. Hedley has contributed to the Proceedings of the 

 Linnean Society of New South Wales (Second Series, vol.vii.) an 

 interesting paper on the range of Placostylus, which he describes 

 as a more fruitful subject of study than any other moUuscan 

 genus inhabiting the same area. Their large and handsome 

 shells have attracted the attention of the most superficial and 

 unscientific collectors, so that an extensive series has been 

 brought to the knowledge of investigators from remote localities. 

 In the summary of his results, Mr. Hedley remarks, first, on 

 the essential unity of the Placostylus area as a zoological pro- 

 vince, embracing the archipelagoes of Solomon, Fiji, New 

 Hebrides, Loyalty, New Caledonia, Norfolk I. (?), Lord Howe, 

 and New Zealand ; a unity explicable, he thinks, only on the 

 theory that they form portions of a shattered continent and are 

 connected by shallow banks formerly dry land. This conti- 

 nental area he proposes to call the Melanesian plateau. He 

 holds, secondly, that this Melanesian plateau was never con- 

 nected with, nor populated from, Australia, but that its fauna 

 was probably derived from Papua viA New Britain. The pre- 

 sence of genera common to Australia and New Zealand he 

 believes to be explicable on the ground that they migrated, not 

 from the one territory to the other, but each from a common 

 source. New fiuinea. Thirdly, he thinks that New Zealand 

 and New Caledonia were early separated from the northern 

 archipelagoes and ceased to receive overland immigrants there- 

 from. Fourthly, the Fijis, according to Mr. Hedley, remained 

 to a later date in communication with the Solomons, but were 

 severed from that group before the latter had acquired from 

 Papua much of its present fauna. 



The " Year Book of Australia " for 1893 has been pub- 

 lished. It includes an interesting account of scientific work 

 done in the various Australian colonies during 1892. This has 

 been compiled from information supplied by the scientific 

 societies of Australia. 



Some valuable reports on the Victorian coalfields, by Mr. 

 James Stirling, of the Geological Survey of Victoria, have been 

 issued by the Department of Mines in that colony. They are 

 fully and most carefully illustrated. 



A French translation of Lord Kelvin's "Popular Lectures 

 and Addresses " has been published by Messrs. Gauthier- 

 Villars et Fils. The translator is P. Lugol, who has added 

 some notes. Translations of extracts from recent memoirs by 

 Lord Kelvin, with notes, have been contributed by M. 

 Brillouin. 



A FRESH instalment of the Proceedings of the American 

 Academy of Arts and Sciences (New Series, vol. xix.) has just 

 been published. It covers the period from May 1891 to May 

 1892. Among the contents are some considerations regarding 

 Helmholtz's theory of consonance, by C. R. Cross and H. M. 

 Goodwin ; a note on the dependence of viscosity on pressure 

 and temperature, by C. Barus ; what electricity is : illustrated 

 by some new experiments, by W. W. Jacques ; on a theorem 

 of Sylvester's relating to non-degenerate matrices, by H. Taber ; 



NO. 1228, VOL. 48] 



researches on the volatile hydrocarbons, by C. M. Warren ; 

 descriptions of new plants collected in Mexico by C. G. 

 Pringle in 1890 and 1891, with notes upon a few other species, 

 by B. L. Robinson ; on some experiments with the phonograph, 

 relating to the vowel theory of Helmholtz, by C. K. Cross and 

 G. V. Wendell, and other papers. 



A PAPER entitled "Further Studies of Yuccas and their 

 Pollination " has been contributed by Mr. W. Trelease to the 

 fourth annual report of the Missouri Botanical Garden, and is 

 also published separately. It is well illustrated. 



The new number of the Quarterly Journal of the Geological 

 Society includes the text of the anniversary address of the Pre- 

 sident, Mr. W. H. Hudleston, F. R.S. He deals with the 

 work brought before the Society in the course of the last seven 

 years, during which he has served the Society in one official 

 capacity or another. 



A FOURTH edition of "Practical Physics," by R. T. 

 Glazebrook and W. N. Shaw, has been issued by Messrs. 

 Longmans, Green, and Co. The authors have taken advantage 

 of this opportunity to make some alterations and additions sug- 

 gested by their own experience or that of their successors at ;he 

 Cavendish Laboratory. 



In a recent number of the Comptes Rendus, M. Rigollot gives 

 a further account of his experiments on the electrochemical 

 actinometer. He finds that the electromotive force developed 

 when light falls on a plate of oxydised copper immersed in a 

 solution of a metallic iodide, bromide or chloride can be con- 

 siderably increased if it has previously been dipped in some 

 colouring matter, such as eosine or safranine. This increase of 

 sensitiveness is different for rays of different wave lengths, and 

 those rays which produce the maximum effect, for any one 

 colouring substance, depend on the position of the absorption 

 band in the light which is transmitted by that substance. 



M. Chassagnv has a note in the current number of the 

 Comptes Rendus on the influence of longitudinal magnetisation 

 on the electromotive force of an iron-copper thermo-electric 

 junction. Two couples were used, one being in the axis of a 

 long magnetising helix, so joined together that they acted in 

 opposite directions. The results obtained were: — (i) The 

 effect of longitudinal magnetisation is always to increase the 

 electromotive force. (2) This increase is independent of the 

 direction of magnetisation. (3) For increasing fields the in- 

 crease is at first very nearly proportional to the strength of the 

 field, and attains a maximum value of 61 microvolts for a field 

 of 55 C.G. S. units. After this it slowly decreases till for a 

 field of 200 units it is 3 2 microvolts. 



At the meeting of the Socicte Francaise de Physique, held 

 on April 21, M. P. Curie gave some of the results of his 

 experiments on the magnetic properties of bodies at different 

 temperatures. The body to be experimented on was placed in 

 a non-uniform magnetic field and the force acting on it 

 measured by the torsion of a metallic wire. An electric heater 

 capable of raising the temperature of the. body to 1400" C. was 

 used, together with one of Le Chatelier's thermo-elements to 

 measure the temperature. In the case of oxygen, the magnetic 

 permeability is constant for magnetising forces of from 200 to 

 1350 units, and for pressures of from 5 to 20 atmospheres. 

 The law of variation of the permeability with temperature is 

 very simple, since between 20° and 450° it varies inversely as the 

 absolute temperature. In the case of air, the permeability at a 

 temperature t is given by the formula loVr = 2760//'-', which 

 can be used to correct observations made in air at any tem- 

 perature. 



