6;8 



NA TURE 



[October 24, ,1901 



readily gives this blue compound at the negative pole. A 

 solution of ammonium iodide in liquid ammonia was now sub- 

 stituted for the potassium salt, and then electrolysed at - 95° C, 

 but no blue coloration was produced, hydrogen gas being 

 steadily evolved from the commencement of the experiment. 

 Thinking that perhaps an increase of pressure might have the 

 desired effect the tube was sealed up, but although in one 

 case the pressure rose to as much as 60 atmospheres before the 

 tube burst, there was still not the slightest evidence of the 

 existence of the radical ammonium in the free state. 



The same number of the Berichle contains an interesting 

 paper, by H. Biltz, on the dissociation of the sulphur molecule. 

 In recent years it has been shown by numerous researches that 

 the maximum density of sulphur vapour corresponds to a 

 molecule S, and not Sg as usually represented in the text-books. 

 But although this point is now well established, there was still 

 a doubt as to the exact manner in which the molecule dissoci- 

 ated, the results of the first measurements of Biltz suggesting 

 that the dissociation actually took place in two stages, the 

 molecules .Sg first breaking up into S,; and S;,, and these S,; 

 molecules finally splitting up into 3S.J molecules. In order to 

 set this point at rest further measurements were carried out, the 

 results of which are given in the present paper. The problem 

 can be attacked in two ways ; the densities can be determined 

 at constant pressure, or at constant temperature with varying 

 pressures. The latter method, giving isotherms, was selected 

 as being capable of the greater accuracy, experiments being 

 carried out at a temperature of 444° C. and at pressures between 

 14 and 540 mm. of mercury. The author concludes that only 

 two kinds of sulphur molecules exist, S, and S.., the former 

 being the only ones present in sulphur solutions, the latter in 

 sulphur gas at temperatures above 850° C. 



A REPORT has been drawn up for the Franklin Institute on 

 recent advances in the physics of water, by Dr. George Flowers 

 Strading, and is published in the Journal of the Institute for 

 October (pp. 257-269). It deals with the theory which 

 assigns to water a complex molecular constitution, the maximum 

 density and its dependence on the pressure, the relations between 

 the pressure, volume and temperature, and the viscosity. In 

 connection with the molecular constitution of water, the author 

 discusses at some length Rontgen's theory, which regards water 

 as consisting of two kinds of molecules called "ice molecules" 

 and " molecules of the second kind." A subject somewhat allied 

 to the above, namely the freezing points of solutions, was recently 

 dealt with in the Physical Review by Messrs. E. H. Loomis 

 and W. F. Magie. 



The Mathematical Gazette contains a brief account of the 

 recent " Teaching of Mathematics " discussion by Mr. R. F. 

 Muirhead, and a paper on the slide-rule by Prof. F. R. Barrell. 

 We should like to see more matter of this kind in the pages 

 of the Gazette, which, it may be remembered, is the organ of 

 an association which till recently called itself the Association for 

 the Improvement of Geometrical Teaching. The present is an 

 opportune time for the Association to resume the functions 

 expressed by its old title, and the fact that many of the members 

 are engaged in teaching mathematics on conventional lines 

 would add to the value of any opinions expressed in the Gazette. 



In a note contributed to the Lombardy Rendiconti, xxxiv. 

 16, Signor Alberto Dina compares the hysteresis in iron under 

 a rotating, an alternating, and a statical magnetic field. In the 

 first the magnitude of the inducing force remains constant and 

 its direction varies, in the second and third the direction remains 

 constant while the magnitude varies. The third case is distin- 

 guished from the first and second by the property that the 

 complete cycle takes place much more slowly. The present 

 NO. 1669, VOL. 64] 



experiments differ from those previously made in that the same 

 body has been used in measuring each of the three kinds of 

 hysteresis. The table of results shows clearly the behaviour of 

 these different forms of hysteresis for equal induction ; while 

 the "alternating hysteresis" is always greater than the "statical 

 hysteresis," the "rotatory hysteresis" lies between both of 

 them until B = 10,000 units approximately ; it then becomes 

 equal to the statical, and afterwards less, and both the per- 

 centage difference and the absolute difference increase as the 

 induction increases. These experiments were performed with 

 iron of low permeability, and it is suggested that similar 

 experiments with soft iron might yield .interesting results. 



Ix addition to papers dealing with meteorological and physical 

 subjects, Nos. i and 2 of the Bulletin of the Moscow Society 

 of Naturalists for 1901 contain an important article by J. J. 

 Gerassimow on the influence of the nucleus on the growth of the 

 cell, and also one by Prof. D. Sernoff on the morphological 

 nature of the tail-like appendages occasionally met with in the 

 human race. After describing, with illustrations, several 

 examples of these appendages, the latter author comes to the 

 conclusion that they are teratological and in no sense atavistic. 



In the Biologischcs Cenlralblatt for October, Dr. G. von Linden 

 commences an account of his investigations into the structure 

 of wings of insects, especially the Lepidoptera during the 

 pupal stage, in relation to their origin and their bearing on the 

 phylogeny of the different groups. The subject has been taken 

 up where it was left by Schiifer, van Bammelen, Haase, Urech 

 and Eimer, and the theory of the latter that the original type of 

 coloration in Lepidoptera was in the form of longitudinal stripes, 

 while a uniform coloration is the final development, is con- 

 firmed. The bearing of the investigation on classification is left 

 for a later communication. 



In the Victorian Naturalist for September Mr. W. Mac- 

 gillivray concludes his notice of North Queensland birds, while 

 Mr. R. Hall gives a further instalment of his notes on unde- 

 scribed nests and eggs of Australian birds. 



We have received a copy of a paper by Miss N. Evans on the 

 habits of the common grey mosquito of Calcutta (Ciilex fatigans), 

 published in the August issue of the Proceedings of the Asiatic 

 Society of Bengal. It is shown that the adult female may 

 live for about five weeks, during which it may feed five times, 

 when it selects by preference the blood of the house-sparrow. 

 The latter fact suggests the possibility of this insect being a 

 carrier of a definite blood-infection. 



The additions to the Zoological Society's Gardens during the 

 past week include a Black-headed Lemur {Lemur bruHneus), a 

 Vellow-cheeked Lemur {Lemur xanthomystax) from Mada- 

 gascar, presented by Mr. S. Neven Du Mont ; two Arctic 

 Wolves [Caiiis occidentalis) from New Mexico, presented by 

 Mr. William Ruston ; three Shaw's Gerbilles {Gerbillus shawi), 

 a Dwarf Jerboa {Dipodillus campestris) from North Africa, pre- 

 sented by Mr. J, S. Whitaker ; a Campbell's Monkey (Cerco- 

 pilhecus campbelli) from West Africa, two White-fronted 

 Capuchins [Cebus albifrons) from South America, a Green- 

 headed Tanager {Calliste tricolor) (torn South-east Brazil, two 

 Dinca Finches {Dinca grisea) from Chili, a South Albemarle 

 Tortoise ( Testndo viciita) from the Galapagos Islands, a Rough 

 Terrapin (Nicoria punctularia) fromiNorthern South America, 

 two Annulated Terrapins (Nicoria annulata) from Western 

 South America, two Menobranchs (Necturus macuiatiis) from 

 North America, two Dark Green Snakes (Zameuis gemoiieiisis), 

 a Four-lined Snake [Coluber i/uatuorliueatus), European ; ten 

 Snake Fishes (Polypterus senegalus) from the White Nile, East 

 Africa, deposited ; a Black-faced Spider Monkey {Ateles ater) 

 from Eastern [Peru, eight Golden Plovers (Charadrius 

 phwialis), European, purchased. 



