March i6, 1905 J 



NATURE 



479 



coetVicients in its irreducible components : Prof. W. 

 Burnside. The first part of the paper contains a deter- 

 mination of the number of times that any given irreducible 

 component occurs, when any representation of a group of 

 finite order as a transitive permutation group is completely 

 reduced. The second part of the paper is occupied with the 

 actual reduction of the permutation group. The reduction 

 takes two forms according as the domain of rationality is 

 defined by the characteristics, or by the roots of unity of 

 which the characteristics are functions. — On the theory of 

 the logarithmic potential : Prof. T. J. V\. Bromwich. 

 The paper is occupied with the conditions for the existence 

 of the second differential coefficients of the potential within 

 an area carrying surface-density, and of the first differential 

 coefficients of the potential on a curve carrying line-density, 

 .^t a corner of the area in the first case, or of the curve 

 in the second, the differential coefficients in question do not 

 exist unless the axes of coordinates have certain special 

 directions. — .Mternntive expressions for perpetuant types ; 

 P. W. Wood, — An informal communication on the theory 

 of geodesies was made by Prof. Forsyth. 

 Cambridge. 

 Philosophical Society, February 27. — Mr. F. II. Neville 

 in the chair. — Soluble forms ol metallic dihydro.xytartrates : 

 H. J. H. Fenton, F.R.S. Sodium dihydroxytartrate is re- 

 marlvable for its very sparing solubility in water, and it 

 has previously been shown by the author that this property 

 may be made use of for the qualitative and quantitative 

 estimation of sodium. When equivalent quantities of 

 dihydroxytartaric acid and sodium ethylate are mixed in 

 alcoholic solution a semi-transparent gelatinous precipitate 

 is obtained which is altogether unlike the salt above 

 mentioned and is extremely easily soluble in water. Its 

 aqueous solution after standing for a few minutes deposits a 

 white, crystalline precipitate of the sodium salt in its ordinary 

 hydrated form. The calcium salt shows a similar behaviour, 

 and it would appear that the ordinary metallic dihydroxy- 

 tartrates must be regarded as derivatives of a hvdrated form 

 of the acid CjHjO,,. — Studies on unsaturated ketonic com- 

 pounds : S. Ruhemann. The author has continued his re- 

 searches on the combination of mercaptans with unsaturated 

 ketones (see Trans. Chem Soc, 1905, Ixxxvii., 17). In the light 

 of previous researches, an explanation is given of the catalytic 

 action of organic bases in the formation of additive products 

 of mercaptans with unsaturated ketonic compounds. — Some 

 compounds of guanidine with sugars : R. S. Morrell and 

 A. E. Bellars. The addition of guanidine to a solution of 

 any sugar in absolute alcohol causes a precipitate of an 

 addition product of the sugar and the base. The compounds 

 are only slightly hydrolysed in aqueous solution, but they 

 are easilv decomposed by acids. Their optical properties 

 are peculiar ; in some cases the rotation angle is opposite 

 in sign to that of the parent sugar, in others there is a 

 marked multi-rotation. — The influence of strong electro- 

 magnetic fields on the spark spectra of some metals: J. E. 

 Purvis. The electromagnet is an exceptionally strong one. 

 The pole pieces are conical, and the strength of the field 

 between the two poles with a current of 25 amperes is 

 40,000 C.G..S. units. It was placed in such a position that 

 a line joining the poles was perpendicular to a line drawn 

 from the slit to the grating. The metals of which an 

 account is given are gold, bismuth, antimony, lead, and 

 tin. The results so far show that amongst the various lines 

 a considerable number are divided into triplets ; whilst, of 

 those which do not show any division, some seem to be 

 widened when the spark is in the field. By analysing the 

 divided lines by means of a calcite crystal, the components 

 do not seem to be polarised in the same way ; i.e. the outside 

 components of one triplet are vibrating perpendicular to the 

 lines of force, whilst those of another are parallel to the 

 lines of force, and the same applies to the inner component. 

 Some lines appear as doublets ; but in many cases most 

 probably the doublets are reversals, and these phenomena 

 are particularly marked amongst the lines of antimony and 

 bismuth. It will be necessary to study these with the 

 magnet placed "end on." Two lines may be very close 

 together, one stronger than the other, and the stronger line 

 will be divided into three, whilst the weaker one is slightly 

 widened only. The work is still in progress, and with other 

 metals. 



NO. 1S46, VOL. 71] 



Paris. 

 Academy ol Sciences, March 6. — M. Troost in the chair. 

 — The president read a telegram from Dr. Jean Charcot 

 concerning the work of the Antarctic Expedition. — On the 

 orthogonal trajectories of a family of surfaces : Gaston 

 Darboux. — .\ rational formula for the coefTicient of ab- 

 sorption of light by a translucent body ; J. Boussinesq. 

 — The study of i-methyl-4-benzylcyclohexanol and i-methyl- 

 4-dibenzylcyclohcxanol : A. Haller and F. March. Meihyl- 

 cyclohexanone reacts with sodium derivatives of alcohols in 

 a manner resembling camphor, the sodium derivative of 

 benzyl alcohol giving a mixture of methyl-benzyl- and 

 methyl-dibenzyl-hexanol, separable by fractional distillation 

 in a vacuum. — Eiimedon convicior, a crustacean accom- 

 panying a sea-urchin : E. L. Bouvier and G. Seurat. 

 The Eumedon occupies a pouch near the anal region of 

 the sea-urchin, and is well protected by the long spines 

 of the latter. The crustacean is not parasitic on its host, 

 the relations between the two closely resembling those 

 holding between Pionodesmotcs phormosoae and the sea- 

 urchin Plionnosoma uramis'. — On the constitution of sun- 

 spots : Th. Moreux. -A discussion of the penumbra of the 

 large sun-spot of January, 1904, of which a drawing is 

 given. The second penumbra, attributed by some observers 

 to irregularities in the nucleus of the spot, is clearly shown, 

 and the author regards this as an additional proof of the 

 theory advanced by him in June, 1900. — On sliding friclion : 

 L. Lecornu. The author considers that the law of 

 Coulomb cannot be regarded as rigorously true, but is 

 rather an empirical rule only roughly approximate. — The 

 oscillations of railway carriages on their springs : Georges 

 Marie. The author has deduced a relation between the 

 periodic variations in level of the permanent way, the 

 friction of the spring, and the deflection of the spring, and 

 has applied this experimentally to various classes of rolling 

 stock, .^s a rule, the condition of convergence was realised, 

 but there were a few faulty vehicles in which this was not 

 the case. — On the determination by the chronometer of 

 differences of latitude at Madagascar and Reunion : M. 

 Driencourt. The data given have a probable accuracy 

 of 01 sec. This precision is rarely attained in such 

 measurements, and details of the working mfthods are 

 given. — On the determination of gaseous densities and the 

 accuracy possible in such measurements : .^. Leduc. For 

 the more permanent gases the author regards the possible 

 accuracy in the density as about i in 10,000 ; for the more 

 easily condensable gases the probable accuracy is lower. 

 The results recently published by MJM. Moissan and 

 Chavanne, Moissan and Binet du Jassoneix, Guye and 

 Pintza, and Jacquerod and Pintza are criticised. — The 

 action of radium bromide on the electrical resistance of 

 metals : Bronislas Sabat. Bromide of radium, placed near 

 wires of bismuth, iron, steel, copper, platinum, brass and 

 German silver, increases their electrical resistance. This 

 effect cannot be wholly attributed to the rise of temperature 

 caused by the radium salt. — Contribution to the study of 

 ionisation in flames : Pierre Massoulier. Previous ex- 

 perimenters have employed electrodes placed one above the 

 other in the flame, and the dissymmetry thus necessarily 

 introduced partially masks the results. The author employs 

 vertical electrodes placed symmetrically in the flame, and 

 the reversal of the field is then without effect on the course 

 of the phenomena. Curves are given showing the relation 

 between the distances from the electrodes and the fall of 

 potential. — The variations of the equivalent spark of an 

 X-ray tube : S. Turchini. — On the time that appears before 

 precipitation appears in solutions of hyposulphites : Gaston 

 Gaillard. — On the electrolytic solution of platinum in 

 sulphuric acid : Andre Brochet and Joseph Petit. Plat- 

 inum is dissolved in sulphuric acid under the action of a 

 variable current, and the action of the alternating current 

 is not specially due to the change in the sense of the 

 current. In the presence of an oxidising agent the solution 

 of the platinum is impeded. — A comparison of the physical 

 properties of pure nickel and cobalt : H. Copaux. Nickel 

 and cobalt have been obtained practically free from other 

 metals, and containing only one or two thousandths of 

 non-metallic impurities. They are magnetic, very crystal- 

 line metals, not malleable in the cold. They differ in ap- 

 pearance, cobalt being bright, res-mbling silver, whilst 

 nickel is dull. Determinations of the density, hardness, 



