440 



NA TURE 



{April I, 1875 



with water at various temperatures and in various proportions. 

 When two salts to which either the acid or the base is common, 

 and which do not form a double salt, are mbced in equivalent 

 proportion, the cryogen produced has nearly the temperature 

 due to the salt, which alone would produce the greatest de- 

 gree of cold. Solidification begins at a temperature below the 

 melting-point of the least fusible, and continues at lower and 

 lower temperatures until the temperature due to the other con- 

 stituent salt is reached. Occasionally a cryohydrate having a 

 constant solidifying point has been obtained by mixing in definite 

 proportions salts \vhich are not known to exist in the form of a 

 double salt. In all such cases tlie solidifying point of the mix- 

 ture is intermediate between the solidifying points of the consti- 

 tuents, and its temperature as a cryogen is also between the 

 temperatures of the constituents when separately used as cryogens. 

 When two salts composed of different acids and bases are mixed, 

 and no precipitation occurs, it is generally considered that partial 

 double decomposition takes place, two new salts being formed. 

 It was found that if the salts A X and B Y be mixed in atomic 

 proportion and dissolved in the smallest possible amount of 

 water, a mixture identical with that produced on mixing A Y 

 with B X is obtained. The temperature and composition of the 

 resulting cryohydrate are the same in both cases. But the tem- 

 perature never falls as low as the point which could be reached 

 by employing wliicheverof the salts A X, AY, B X, B Y, forms 

 a cryohydrate with the lowest temperatm-e. Thus a saturated 

 solution of a mixture of nitrate of potassium and sulphate of 

 sodium solidifies at - 5' C. A mixture of nitrate of sodium and 

 sulphate of potassium also solidifies at this temperature. Since 

 the solidifying point of nitrate of sodium is - 17°, this salt 

 cannot exist without partial decomposition taking place in either 

 mixture ; for, as has been shown above, its presence would ulti- 

 mately depress the solidifying point. Dr. Rae remarked that these 

 researches are speciallv interesting in connection with the salts 

 retained by sea-ice. With a view to study this subject, he has 

 already requested captains of whalers visiting the Arctic regions 

 to bring heme samples of ice of different age and from various 

 localities. 



Pakis 

 Academy of Sciences, March 15. — M. M. Fremy in the 

 chair. — The following papers were read :- On electro-capillary 

 action and the intensity of forces producing it, by M. Becquerel 

 (fourth paper on the subject). — A note by H. Sainte Claire 

 Deville, on the alloys of platinum and iron. — Researches on the 

 fatty acids and their alkaline salts, by M. Berthelot. The subject 

 is treated at length, and the formation of sodium, ammonium, and 

 barium salts, both in solution and in the solid state, is considered. 

 — On acetic anhydride, by the same ; account of new experi- 

 ments to determine the heat evolved during the transformation 

 of acetic anhydride into acetic acid. — A note by M. de Lecaze- 

 Dulhiers, on the origin of the vessels in the tunica of simple 

 Ascidia. — On the simultaneous formation of several mineral 

 species in the tliermal source of Bourbonne-les-bains (Haute- 

 Marne), specially of galena, anglesite, pyrites, and silicates of 

 the zeolite family (notably of chabasite), byM. Daubiee (second 

 paper). — On a peculiar mode of excretion of gum arable, by the 

 Acacia ]'crck of the Senega], by M. Ch. Martins. — Report by 

 M. Milne-lidwards, on the measures proposed to prevent the 

 invasion into France of the American insect Doryphora, which 

 destroys the potatoes. — M. Moucliez, the chief of the expedition 

 sent to St. Paul to obseive the transit of ^'enus, ^^a3 then 

 received by the President, who welcomed him in the name of 

 the Academy. M. Mouchez read a long paper on the subject, 

 giving all the details of the transit. lie specially described the 

 opiical phenomtna observed in the vicinity of the contacts, and 

 brings home no less than 489 photographic proofs that can all be 

 utilised for niicrometrical measurements. The two interior con- 

 tacts were observed with great precision, the two outeroneshaving 

 been rather spoiled by clouds. Altogether this expedition may be 

 considered highly successful. — On the geometrical solution of 

 some new problems relatmg to the theory of surfaces, and de- 

 pending upon infinitesimals of the third order, by M. Mannheim 

 (second paper). — On the simplest modes of limit equilibritim 

 which can be present in a body without cohesion and strongly 

 compressed ; application to a mass of sand filling the angle 

 between two solid planes and movable round their line of inter- 

 section as axis ; by M. J. Boussinesq. — A memoir on the 

 formula; of perturbation, by M. Emile Mathieu. — Micrographic 

 study on the manufacture of paper, by M. Aime Girard. — On 

 the action of sulphite of ammonia m the culture of beet-root, 

 by M. P. Lsgrange. — A note by M. F. Fouque, on the nodules 



of woUastonite, fassaite pyroxene, melanite garnet of the 

 Santorin lava. — On the immediate treatment of intestinal ob- 

 struction, by the aspiration of the gases from the intestines, by 

 M. Demarquay. — A memoir, by M. Michal, on the determina- 

 tion of the results of several observations, with special reference 

 to the precision of the result. — A note, by M. L. Berthout, on the 

 discovery of a deposit of fossils in the plain of Ecouche, in the 

 arrondissement of Argentan (Ome). — A number of members 

 then made various communications on Phylloxera. — The Minis- 

 ter of Public Instruction addressed to the Academy a project of 

 a medal in commemoration of the Transit of ^'enus. — The 

 Minister of Public Works sent a report of the Commission 

 charged with the proposal of measures to be adopted to prevent 

 the infection of the River Seine in the neighbourhood of Paris. — 

 On certain left perspectives of plane algebraic curves, by M. 

 Halphen. — On some properties of curves traced on surfaces, by 

 M. Ribaucour. — On diffraction and the focal properties of nets, 

 by M. A. Comu. — On the magnetising function of tempered 

 steel, by M. Bouty. — On the determination of the quantity of 

 magnetism in a magnet, by M. R. Blondlot. — On the theory of 

 storms ; a reply to M. Faye, by M. H. Peslin. M. Faye, who 

 was present, then made some observations on the same subject. — 

 On some double stars whose motions are rectilinear, and are due 

 to a difference in proper motion, by M. C. Flammarion. — On 

 the identity of the bromo-derivatives of the hydrate of tetra- 

 bromethylene with those of perbromide of ace'.ylene, by M. E. 

 Bourgoin. — On the quantities of heat evolved in the decompo- 

 sition of the chlorides of some acids of the fatty series, by M. 

 L. Longuinine, specially referring to butyric, isobutyric, and 

 valeric acids. — On amylogene, or soluble starch, by M. L. Bon- 

 donneau. — On a new method of volumetric analysis of liquids, 

 by M. F. Jean. — Chemical researches on the absorption of the 

 ammonia of the atmosphere by the volcanic soil of the solfatara 

 of Puzzola, by M. S. de Luca. — A reply to two recent commu- 

 nications of M. Bechamp, relative to spoutaneous alterations of 

 eggs, by M. U. Gayon. — Observation of the life of Hclodcnna 

 hcrriduiii, Wiegmann, by M. Sumichrast, reported by M. 

 Bocouit. — On the helminthological fauna of the coasts of Brit- 

 tany, by M. A. Villot. — Critical observations on the classifica- 

 tion of Pala-jzoic Polyps, by M. G. Dollfus. — MM. Dumay and 

 Martin de Brettes then made some communications relatmg to the 

 bolide seen on February 10 last. —A note, by M. Neyreneuf, on 

 the combustion of explosive bodies. — A number of scientific 

 works were presented to the Academy by several gentlemen. 



BOOKS AND PAMPHLETS RECEIVED 



Colonial. — Microscopical Notes regarding the Fungi present in Opium 

 Blight: D. V, Cunninghim, MB., Surgeon H.M. Indian Medical Service 

 (Calcutta). — Geological Survey of Canada ; Repjrt of Progress lor 1873-74 

 (I>awson Brothers, Montreal). 



CONTENTS Page 



Deep-Sea Fishing 421 



J ARDINE'S " PSVCHOLOGY OF COG.MTION." liy DoCGLAS A. SpALDING 422 



White's "Seluorne" 423 



OUK Book Shelf :— 



Cunningham's " Opium Blight Fungi" 4-4 



Bottomlcy's " Logarithmic lables" 424 



Letters to the Editor : — 



AGyrostat Problem— Answer ((f'iV/i///«j/ra//('«) — D. M'Farlane 424 



The Sounds of the String Organ. — Hhk.mann Smith 425 



The Law ol Muscular Exhaustioa and Restoration.— G. HlNRlCHS 426 



The Height of Waves —Arthur R. Gk-anville 427 



Thermometer Scales.— S. G- Denton 427 



Accidental Importation of Molluscs and Insects.— Dr. F. BttCHANAM 



White 427 



Fall of a Meteor at Orleans. — Herbert M'Lbod 427 



Proposed Aquarium in Edinburgh. — R.\lph Richardson . . . 427 



Acherontia Atropos. — Fred. P. Johnson 427 



Destruction of Flowers by Birds. — P. iJ. M 428 



Our Astronomical Colu.mn : — 



Southern Double Stars 428 



Variable Stars 428 



Minor Planets 428 



Daniel Hanbuky, F.R.S 428 



Twentv-Three Hours in the Air. By W. de Fonviklle . . . 429 

 On a Propeller imitati.sg the Action of the Fin of the Pipb- 



FisH. By Prof. A. H. Garrod (<Kj'M////«/rar/onj) 429 



The New Standard Sideseal Clock of the Rov.al Observatory, 



Greenwich (With I Uustratum) 431 



ARCTIC Vegetation 433 



Notes .... 434 



Accidental ExpLosio.vs. By Prof. F. A. Abel, F.R.S 436 



Societies and Academies 450 



Books and Pa.mphlets Received 440 



-Vol. 



p. 403, col. 



I and 



from bottom, for 



