December i6, 1920J 



NATURE 



521 



Uffined limits. It was pointed out that silver solu- 

 tions in existence more than sixty years still continued 

 to yield excellent results, and that, generally, old 

 solutions yielded better deposits at higher current 

 densities than those newly made up from pure 

 materials. This was due in a great measure to the 

 presence of substances other than the simple double 

 cyanide of silver and potassium, especially potassium 

 carbonate. — G. B. Brook and L. \V. Holme* : The 

 chemical composition of old silver-plating solutions, 

 with observations on their working properties. The 

 paper dealt with a large number of solutions varying 

 in age from one to fifty years, furnishing historical, 

 chemical, and physical data with regard to each, and 

 correlating the composition with the working pro- 

 perties in actual works practice. — F. Mason : .\ new 

 maximum current density in commercial silver-plating. 

 With a free cyanide content in excess of that usually 

 advised, and with potassium carbonate in considerable 

 quantities, not only can the current density be in- 

 creased enormously, but the deposit is of an excep- 

 tionally fine texture and takes a high finish. — G. B. 

 Brook ■ The crystalline structure of electro-deposited 

 -ilver. — S. FleW : The deposition of gold-silver alloys, 

 series of experiments has been carried out in order 

 trace the influence of v,'irying conditions on the 

 composition of the gold-silver alloys deposited in the 

 well-known "green gold." 



DlJBUN. 

 Royal Doblin Society, November 23. — Dr. F. E. 



I lai ktlt in the chair.— Prof. H. H. Dixon and Nigel G. 

 Ball : .A determination, by means of a differential 

 calorimeter, of the heat produced during the inver- 

 sion of sucrose. The heat of inversion of sucrose in 

 presence of invertase was determined by means of a 

 differential calorimeter in which the temperature was 

 measured with a sensitive thermocouple. Two 

 icuum flasks were employed, in one of which the 

 iction took place, while the other was used as a 

 :ilrol, one junction of the thermocouple being in 

 A\ flask. The enzyme solution was contained in 

 rapsule of paraffinf>d paper immersed in the sugar 

 -■rlution to secure that both were at the same ttm- 

 • r.iture. In the control flask a similar arrange- 



■ nt was used, but the enzyme solution had been 



■ viously heated to 100° C. These capsules could 



ruptured without opening the flasks. The tem- 



rature effects of dilution of the sucrose were 



iriinatfd bv these arrangements. Stirring was 



!■ rted by shaking the flasks. \ value for the heat 



Kluced during the inversion of sucrose by invertase 



1-. obtained which ' agrees closelv with that 



viously given by Brown and Pickering, the mean 



the results bring 383 calories per grain-molecule. 



Paris. 



Academy el Sciences, November 22.— M. Henri 

 Dcsl.-mdres in the chair.— .\. T. Schloeiln(J : The 

 paration of two salts having a common ion. In 

 preparation of ammonium nitrate from sodium 

 rate and ammonium bicarbonate an aqueous solu- 

 n of sodium nitrate and ammonium nitrate is 



■ lained, from which the latter salt has to be cx- 

 r.irted. Solubility curves of mixtures of these two 



ilts have been worked out and are given in the 



i)iT and the mode of applying these to the problem 



indicated. — K. Imbeanx : New systems of electric 



ving on canals. The haulage difficulties on canals 



iih numerous locks, such as those of the Mnrne, 



'line, and the .Sarre coalfields, arc summarised, 



I a description is given of the systems at present in 



v.. Arits ; The heat of evaporation of a liquid 



at low temperatures. Reply to a note of M. G. 

 Bruhat. — T. Varopoulos : Algebroid functions and in- 

 creasing functions. — J . de Lassus : The essential pro- 

 perties of pneumatic transmission in a closed cycle. — 

 J. Andrade ; The last perturbations of isochronism. — 

 W. Margoulis : A new method of testing aero- 

 dynamic models in gas currents. In existing ap- 

 paratus serious errors may arise, as it is impossible 

 to observe the conditions required by the law of 

 similitude. The author suggests the replacement 

 of air by carbon dioxide at high pressures and 

 temperatures, and gives formulae showing the 

 resulting reduction in the horse-power of the 

 motor necessary for moving the gas. — Lord 

 Rayleigh : The light diffused by argon. Remarks on 

 a recent paper by M. J. Cabannes. — C. Matlgnon and 

 M. Frijacque* : The transformation of ammonia into 

 urea. The problem of the economical trans- 

 formation of ammonia into urea is of undoubted 

 technical interest, since- it contains 47 per cent, 

 of nitrogen as against 35 oer cent, of nitrogen 

 in ammonium nitrate, and it behaves _ as an 

 "excellent manure. .An account is given of 

 studies on the conversion of ammonium carbamate 

 into urea. — A. Mugnet and J. Seroin : The age of 

 the autunites of Portugal. These minerals are of 

 recent formation, and were formed between 1250 and 

 1900 vears ago. The figures are based on the deter- 

 mination of the ratio of radium to uranium in the 

 minerals. — G. Denliot : The stratigraphical position of 

 the Montabuzard limestone.— A. Holland : The exist- 

 ence of formations of ground called rideatix in 

 Cantal.— R. Souiges : The embryogeny of the 

 Urticaceae. The development of the embryo in Urtica 

 pilulifera.—.\. Chevalier : The variations of the buds 

 of cultivated trees and shrubs as a cause of decadence 

 of old varieties.— J. Barlot : New colour reactions 

 utilisable for the diagnosis of mycological species. 

 •The colour reaction with potash solution serves to 

 distinguish between the poisonous Mycena pura and 

 the variety ainethystitia of iMccaria laccata (edible). 

 The same solution gives different colour reactions 

 with Gomphidius ghititwsus and G. viscidus. 

 p. Dangeard : Metachromatine and the tannic com- 

 pounds of the vacuoles.— W. Mestreiat and Mile. 

 Marthe Paul-Janet : The comparative evaluation of 

 the total nitrogen in urine bv the methods of Dumas 

 and Kjeldahl. The Kjeldahl' method applied to urine 

 gave onlv from 085 per cent, to 903 per cent, of the 

 nitrogen found bv the Dumas method.— A. Damlens : 

 The toxicological detection of poisons containing 

 bromine. An application of the methods described in 

 previous communications for the detection and 

 estimation of traces of bromine in animal tissues.— 

 G. Bohn and Mme. A. Dnewlna : Variations of 

 sensibilitv to soft water of the Convoluta, according 

 to the physiological states and the number of animals 

 under experiment.— I.. Jonbln and E. Le DanoU : Bio- 

 logical researches on the thermometry of the Atlantic 

 off Ushant during the summer of 1020. The data 

 obtained are represented on two diagrams, showing the 

 <listril)ution of termieralures in a section VV.-N.W. 

 through Ushant.— C. Leballly : The conservation or 

 disappearance of the virulence of apthous milk in the 

 course of the manipulations following treatment. If 

 the contaminated milk is allowed to stand for cream 

 long enough for an incipient lactic fermentation to 

 lake place the virus is attenuate<l or destroyed, and 

 voung animals fed on such milk during an epidemic 

 have either remained healthy or have h.id only a mild 

 attack. When the milk is collected in larjje 

 creameries and the cream auJckly separate<l mechanl- 

 callv. the skim milk rapidfy spreads the frvrr. 



NO ?C)M, VOL. 106] 



