March 8, 1888J 



NATURE 



453 



March i. — " On llie Changes produced by Magnetization in 

 the Dimensions of Rings and Rods of Iron and of some other 

 Metals." By Shelford Bidweli, F.R.S. 



Linnean Society, February i6. — W, Carrulhers, F.R.S., 

 President, in the chair. — Mr. Spencer Moore exhibited, and 

 made some remarks upon, specimens ilhistrative of the Palmella 

 state DrapaniaUia glomerata. — Mr. D. Morris (Royal Gardens, 

 Kew) exhibited a specimen of wood of Hieronyma alchornioides 

 received from Trinidad, showing in its fissures mineral deposits, 

 which on chemical analysis proved to be calcic carbonate. For 

 comparison, Mr. Morris also exhibited and made some observa- 

 tions upon some deposits of calcic phosphate in teak. Some of 

 these (described by Sir Fred. Abel, Quart. Journ. Chem. Soc. xv. 

 91), are 6 feet in length, 6 inches in breadth, and from g inch to 

 % inch in thickness. Deposits in bamboo known as tahasheer 

 (silicate) were shown, as also pearls (carbonate of lime) from cocoa- 

 nuts, received from Dr. Sydney T. Hickson (see Nature, vol. 

 xxxvi. p. 157). All these specimens were from the Museum of 

 Economic Botany of Kew. — Dr. Burn Murdock exhibited and 

 offered remarks upon the intra-marginal (so-called) veins in the 

 section Arcolata of the genus Erjihroxylon, of which E. coca is 

 the most familiar species. These lines are due to a thickening 

 of the parenchymatous tissue which takes place in the bud stage, 

 and are in no way connected with the venation of the leaf. — Mr. 

 G. F. Sherwood exhibited a collection of photographs taken in 

 Samoa, illustrating the scenery and people, together with a 

 number of necklets formed with .'-trings of various bright-coloured 

 seeds.— The first paper of the evening was read by Mr. H. N. 

 Ridley, on self-fertilization and cleistogamy in orchids. Three 

 common methods of self-fertilization were explained : (l) by the 

 breaking up of the pollen mass, and falling of the dust either 

 directly upon the stigma, or into the lips whence it comes into 

 contact with the stigma ; (2) by the falling of the pollen masses 

 as a whole from the clinandrum into the stigma ; and (3) by the 

 falling forward of the pollinia from the clinandrum, or the anther 

 cap, the caudicle and gland remaining attached to the column. 

 An interesting discussion followed, in which Prof. Marshall 

 Ward, the Rev, G. Henslow, and Mr. A. VV, Bennett took 

 part. — A paper was then read by Dr. John Rae, F. R.S., 

 entitled " Notes on some of the Birds and Mammals of Hudson's 

 Bay Territory." Dr. Rae, whose long residence in Northern 

 and Arctic America enabled him to speak authoritatively from 

 personal observation, gave au interesting account of the migra- 

 tion of the Canada goose, snow goose, aud blue-winged goose, 

 and of the habits of the American hare and lemming. He par- 

 ticularly referred to the belief entertained by some of the Indian 

 tribes he had met with, and to which he himself gave credence, 

 that certain species of small birds are assisted on their migrations 

 by being carried on the backs of the Canada geese. Mr. J. E. 

 Harting, in criticising this paper, gave an exposition of the views 

 held by leading ornithologi'Sts on the subject of the American 

 Canada and snow geese, their relationship and nomenclature, 

 and pointed out that the story of small birds being carried by 

 larger ones is not confined to North America, but is current in 

 South-Eastern Europe, Palestine, and Arabia, where trust- 

 worthy evidence has been obtained that wagtails and other small 

 birds travel on the backs of cranes. He added that one in- 

 stance was known to him of such an occurrence in England, a 

 short-eared owl having been seen to arrive on the north coast of 

 Yorkshire carrying on its back a golden-crested wren, which was 

 secured by the observer. 



Chemical Society, February 16. — Mr. W. Crookes, F.R.S. , 

 in the chair. — The following papers were read : — Chemical in- 

 vestigation of Wackenroder's solution, and explanation of the 

 formation of its constituents, by Prof. Debus, F.R.S. Wacken- 

 roder's solution is obtained by passing hydrogen sulphide into 

 an aqueous solution of sulphur dioxide until the latter is decom- 

 posed. It has been considered to contain sulphur in suspension 

 and pentathionic acid in solution, although neither the acid nor 

 its salts have been prepared pure, and, in consequence. Spring 

 has denied the existence of the acid, regarding it as a solution 

 of sulphur in tetrathionic acid. The author finds that Wacken- 

 roder's solution contains: (i) sulphur in suspension in very 

 minute drops, (2) a new allotropic modification of sulphur, 

 (5), in simple solution, and in the colloidal condition, (3) traces 

 of trithionic acid, (4) tetrathionic acid, (5) pentathionic acid, 

 and (6) a polythionic acid containing more sulphur than the 

 penta- acid, probably hexathionic acid. Pure potassium and 

 copper pentathionates were prepared, and the reactions of the 



polythionates studied, among the most interesting of which are 

 the spontaneous changes in aqueous solution shjwn by the 

 equations — 



(a) K,S«0« = K^S.Ob + S; (^)2K,S40„ = \<i,?>;0, + K.,S50„ ; 



{c) 2K2S3OS = K,S40« -f K,S04 -f SO, ; {<i) sKjSjOe = 



K2S5O6 + 2K^S04 -f- 2SO. ; 



the reactions (a) and [l>) occurring in either direction with equal 

 facility. The final products of the action of hydrogen sulphide 

 on tetra- and pentathionic acids are water and sulphur. The 

 polythionic acids can also be obtained by the action of sulphur 

 dioxide on potassium thiosulphate or on the chlorides of sulphur. 

 The concluding portion of the paper was devoted to a discussion 

 of the formulae of the polythionates. — Potilizin's law of the 

 mutual displacement of chlorine and bromine, by Prof. Thorpe, 

 F.R.S., and Mr. J. W, Rodger, On heating bromine with an 

 equivalent quantity of an anhydrous metallic chloride in a sealed 

 glass tube, free from air, to the temperature of the melting-point 

 of zinc, Potilizin found that the amount of chlorine displaced 

 by bromine was greater the higher the atomic weight of the 

 metal in the chloride ; and further, that, if A be the atomic 

 weight of the metal, / the percentage of chlorine displaced from 

 its chloride when treated as above, and E its valency, the 



formula -— ;, = a constant held good in the case of fourteen 

 ph," 



chlorides. To test the validity of this law, the authors heated 

 the chlorides of sodium, potassium, silver, strontium, barium 

 and lead with bromine at 35o°-450°, and found that, with the 

 exception of silver chloride, in which the deviation was not so 

 marked, the amount of chlorine displaced was considerably less 

 than that required by Potilizin's law, and in all cases stood in 

 no definite relation either to the duration of heating or to the 

 atomic weight of the metal of the chloride used, although 

 most chlorine was displaced from the chloride of highest mole- 

 cular weight when several were heated simultaneously. These 

 experiments therefore disprove the validity of Potilizin's law. 

 — A gasometric method of determining nitrous acid, by Dr, P. 

 F. Frankland. Based on the interaction of urea and nitrous 

 acid. — The action of some specific micro-organisms on nitric 

 acid, by the same. The auth )r has investigated the behaviour, 

 when grown in nutritive solutions containing nitrates, of a num- 

 ber of micro-organisms obtained from air and water, and culti- 

 vated in a state of purity. Of thirty-two different forms so 

 examined, sixteen or seventeen, and particularly Bacillus ramo- 

 sus and B. pestifer, were found to reduce the nitrate to nitrite 

 more or less completely, whilst the remainder were quite desti- 

 tute of this power. The behaviour of the organisms was not 

 altered in this respect by excluding air from the solutions in 

 which they were cultivated. — The action of phosphorus penta- 

 chloride on salicylaldehyde, by Mr. C. M. Stuart, — Some inter- 

 actions of nitrogen chlorophosphuret, by Mr. W. Couldridge. — 

 Action of alcohols on ethereal salts in presence of small quan- 

 tities of sodic alkylate, by Prof Purdie and Mr. W. Marshall. 

 — Note on the densities of cerium sulphate solutions, by Dr, B. 

 Brauner, The values of the densities of solutions of the an- 

 hydrous and of the hydrated salt are identical for solutions of 

 equal concentration. 



Erratum. — P. 406, second column, line 9 (from top), for 

 V — («- - i) («- -f 2) readv = («'' - i)/(«^ + 2). 



Physical Society, February 25, — Prof. Reinold, F.R.S., 

 President, in the chair. — The following papers were read : — Note 

 on the efficiency of incandescent lamps with direct and alternating 

 currents, by Prof. W. R. Ayrton, F.R.S., and Prof. J. Perry, 

 F.R.S. This relates to the' question whether the "efficiency" 

 (candles per watt) is greater or less for alternating than for 

 direct currents. Experiments made by Messrs. Shepherd and 

 Wheatley, two of the students at the Central Institution (to 

 whom the authors express their thanks for the valuable assistance 

 rendered) show that no appreciable difference can be detected 

 when the lamp is at the same candle-power. In performing the 

 experiments, three-way switches in connection with Gramme and 

 Ferranti machines were arranged so that the current through the 

 lamp could be quickly changed from direct to alternating, or 

 vice versa, adjustable resistances having been previously placed 

 in the two circuits to give equal readings on a Cardew voltmeter 

 placed as a shunt to the lamp. The currents were measured by 

 a reflecting dynamometer wound with fine wire in order to make 

 the error, due to unequal current density over the section, 

 negligible. The problem has also been investigated from 



