28 



NA TURE 



[July i, 1909 



spheres when in contact. When the charges on the spheres 

 dre +g and — g respectively, and xja is small compared 

 with unity, the attractive force between them is given by 



2f 



«jr(log<{a/^-)r 



approximately. 



— -The effect of previous magnetic history on magnetisa- 

 tion : E. Wilson, G. E. O'Dell, and H. W. K. Jennings. 



It is well known that if a piece of iron be subjected to 

 a considerable magnetising force, and then be tested for 

 permeability corresponding to a lower force, the permea- 

 bility so obtained may differ widely from the permeability 

 which would have been obtained had the material been 

 previously demagnetised. The principal object of this 

 paper is to examine the effect of previous history upon 

 the dissipation of energy by magnetic hysteresis. A ring 

 of iron was carefully demagnetised, and the hysteresis 

 loop No. I, corresponding to a force H, was obtained. 

 The force was then increased to a value H, for the pur- 

 pose of producing previous history, and removed. A 

 hysteresis loop No. 2, corresponding to the force H, was 

 then obtained. As is well known, this loop shows a 

 reduced permeability. The ring was carefully demag- 

 netised, and a hysteresis loop No. 3 obtained as follows. 

 A magnetising force supplied by an additional coil was 

 gradually increased, until on reversal of the original force 

 H a change of magnetic induction exactly equal to that 

 observed in the case of loop No. 2 was obtained. Two 

 loops (Nos. 2 and 3) have now been obtained, each having 

 the same change of magnetic induction and the same net 

 change of force H. The change from loop No. i to loop 

 No. 2 has been brought about by inter-molecular force, 

 whereas the change from loop No. i to loop No. 3 has 

 been brought about by the application of an externally 

 applied constant force. If the effect of inter-molecular 

 force were capable of being exactly equivalent to that of 

 the externally applied const.int force, one would expect 

 to find that the energy required to perform a complete 

 cycle would be the same in each case — that is, the area 

 of loop No. 2 would be equal to the area of loop No. 3. 

 The experiments show that within certain limits the 

 area of loop No. 2 is greater than that of loop No. 3, 

 the difference depending upon the magnitude of the 

 reversed force H and the previous history. 



Mineralogical Society, June i 5.— Principal H. A. Miers, 

 F.R.S., president, in the chair. — Carnotite and an 

 associated mineral-complex from South Australia : T. 

 Crook and G. S. Blake. The carnotite of Radium Hill, 

 near Olary, South .■\ustralia, occurs in a definitelv crystal- 

 line condition. The crystals are tabular and orthorhombic 

 in syinmetry. The carnotite of Colorado, though not so 

 definitely crystalline, also contains tabular crystals which 

 are orthorhombic in symmetry, and probably identical in 

 mineral characters with those of South Australia. From 

 the general characters of these crystals it appears that 

 carnotite is a mineral belonging to the uranite group, and 

 that it may be regarded as the vanadium analogue of 

 autunile. The black lodestuff in which the Radium Hill 

 carnotite occurs is heterogeneous in constitution. It 

 consists essentially of ilmenite, which is impregnated with 

 magnetite, rutile, carnotite, and a mineral which is possibly 

 tscheffkinite. The evidence provided by a study of the 

 complex does not necessitate the view that new minerals 

 are present, such as that to which the name " davidite " 

 has been given. — The species pilolite, and the analysis of 

 a specimen from China : G. S. Whitby. The specimen 

 examined is from a new source, and possesses the formula 

 AI,0,.2SiO,.2fMg0.2SiO,),7H,0, a formula which is 

 simpler than those given by Heddle and by Friedel to the 

 pilolites which they investigated. The author considered 

 that, for the present, the term pilolite should be applied to 

 those varieties of mountain leather and mountain cork 

 which (1) cannot be referred to asbestos, on account of 

 their large water-content ; (2) cannot be identified with 

 serpentinous asbestos, on account of the relatively small 

 amount of magnesia which thev contain ; and (3) hold 

 their water in such a way that, when it has been expelled 

 NO. 2070, VOL. 81] 



by heating, it is gradually re-absorbed to its original 

 amount from the atmosphere. — Phenakite from Brazil ; 

 Dr. G. F. Herbert Smith. Crystals of phenakite recently 

 discovered at the gold mine, San Miguel de Piracicaba, 

 Brazil, all display the new form Izjjij noted by other 

 observers, and another. I4596I, lying near it. The tetarto- 

 hedral character of the symmetry is clearly marked. — 

 Preliminary note on the occurrence of gyrolite in Ireland : 

 F. N. A. Fleischmann. The mineral gyrolite, though 

 well known as occurring in the basalts of the western 

 islands of Scotland, has not hitherto been recorded from 

 Ireland. Specimens have now been found in the basalts 

 and dolerites in the neighbourhood of Belfast. The 

 mineral occurs in small spherical aggregates, forming a 

 crust on faroelite ; it is associated with apophyllite, and 

 occasionally with chabazite. The chemical composition 

 and the optical characters of the mineral agree with those 

 of gyrolite. The mineral is found only in the harder and 

 denser layers of the basalt, and never in the soft, highly 

 amygdaloidal layers. " 



Zoological Society, June 15. — Dr. .^. Smith Woodward, . 

 F.R.S., vice-president, in the chair. — The organ of i 

 Jacobson in Orycteropus : Dr. R. Broom. Orycteropus I 

 has a long narrow organ of Jacobson which opens into " 

 the naso-palatine canal. The arrangement of the cartilages 

 is quite different from the type found in the higher 

 Eutheria, and there is also a marked difference from the 

 arrangement in Dasypus. The general structure comes 

 nearest to that of the marsupials, though there are a 

 number of striking differences. — Some points in the struc- 

 ture of the lesser anteater {J^amandua tetradactyla), with 

 a note on the cerebral arteries of Myrmecophaga : F. E. 

 Beddard. — Decapod Crustacea from Christmas Island, 

 collected by Dr. C. W. .'\ndrews : Dr. W. T. Caiman. — 

 An abnormal individual of the echinoid Amblypneustes : 

 H. L. Hawkins. — The decapods of the genus Gennadas 

 collected by H.M.S. Challenger : S. Kemp. — Notes on a 

 young walrus (Odohaeiuis rosnmrus) recently living in the 

 society's gardens : Dr. P. C. Mitchell. — Notes on the 

 viscera of a walrus (.Odohaenus rosmanis) : R. H. Burne. 



Royal Meteoroligical Society, June 16. —Mr. H. 

 Mellish, president, in the chair. — Interdiurnal variability 

 of temperature in Antarctic and sub-Antarctic regions : 

 R. C. Mossman. The author discussed the day-to-day 

 difference in tin; mean temperature of successive days ut 

 a few places in the Antarctic regions for which the 

 necessary detailed daily observations are available. The 

 greatest mean annual temperatr.i-e variability, viz. 5-9°, 

 was recorded during the " drift " of the Belgica in the 

 ice pack, this high value being closely followed by a mean 

 of 53° at the South Orkneys. In the Victoria Land 

 region, Ross Island and Cape Adare have a somewhat 

 lower temperature variability of 45°, the values of the 

 southern station being higher in summer and autumn and 

 lower in winter and spring than at the northern station. 

 South Georgia occupies an intermediate position between 

 a continental and an oceanic climate in its curve of 

 variability, the mean monthly values varying according to 

 the proximity of the pack ice. At this station the seasonal 

 values show a small variation, and this is also the case 

 at Ushuaia, in Tierra del Fuego. The variability at the 

 Falkland Islands and New Year's Island is very small, 

 pointing to the conserving influence exerted by the insular 

 conditions which prevail at these places. The maximum 

 variability occurs in winter, and the minimum in summer, 

 at the three Antarctic stations, as well as at South Georgia 

 and the South Orkneys. The smallest variability at any 

 season for any station occurs at the South Orkneys in 

 summer, being only 1-4°. It is at this season that cloud 

 amount and fog frequency are at a maximum, while, at the 

 same time, rapidly moving cyclonic disturbances arc of in- 

 frequent occurrence. — ^Temperature records during balloon 

 ascents : E. Gold and Dr. W. Schmidt. The authors 

 described experiments made with the view of ascertaining 

 if appreciable errors could enter into the temperatures 

 recorded In balloon ascents owing to errors in the alcohol- 

 carbonic acid method of testincr the apparatus. — The 

 exposure of thermometers : L. C. W. Bonacina. 



