February 23, 1905] 



NATURE 



407 



originally moving' in the direction of propagation with a 

 velocity slightly less than that of radiation may be picked 

 up by the waves and carried forward with the velocity of 

 radiation. 



The conclusion is that the propagation of disturbances of 

 any form in a straight line involves a sorting of free ions 

 and molecules according to their initial circumstances, and 

 streaming of these both with and against the waves must 

 take place. 



These results are general, and are limited only by the 

 limits of the electrodynamic equations. They suggest, how- 

 ever, a possible explanation of the action of all kinds of 

 ionising agents. 



In particular, it is suggested that if a radio-active sub- 

 stance is an origin from which electromagnetic disturbances 

 are radiated, these disturbances probably ionise the gas in 

 the immediate vicinity and produce streaming of ions and 

 molecules with their associated properties both outwards 

 from and inwards to the substance. This view does not 

 necessarily involve the supposition that there is a continual 

 diminution of the substance. 



The results may also throw some light on the question of 

 the energy sent out. For, suppose that there exist a posi- 

 tive and a negative ion which, in the absence of the pulses, 

 would recombine at some point A, thereby radiating a certain 

 amount of energy, then the directive action of the pulses 

 may make them recombine at some other point B. Thus the 

 radiated energy will proceed from the point B instead of 

 from the point \. The transference of a single free ion can 

 be accomplished without the expenditure of energy, and it 

 is possible that the transference of the positive and negative 

 inns may take place without any abstraction of energy from 

 the pulses. Since, however, in general the transference may 

 involve a relative displacement of the two ions, abstraction 

 of energy from the pulses may be involved, so that the ques- 

 tion is one about which the greatest caution must be exer- 

 cised. It cannot be decided without further investigation. 



These considerations are in general agreement with the 

 views that have been expressed by Lord Kelvin and Prof, and 

 Madame Curie. 



The question whether the apparent velocity of drifting may 

 be of the order indicated by experiment is considered ; and 

 it is shown that in order to give velocities comparable with 

 that of radiation, the theory leads us to expect that the fre- 

 quency of vibration of the waves radiated by the particles 

 should be of the order for visible or ultra-violet light. 



The differences between ionising agents would turn to a 

 considerable extent on the character of the disturbances 

 radiated. 



Since the propagation of waves through a region of space 

 containing matter involves streaming of the matter, the con- 

 tinued propagation cannot be quite independent of any 

 statical, electric or magnetic field present. 



Februarv 2. — " Note on the Determination of the Volume 

 Elasticity of Elastic Solids." By Dr. C. Chree, F.R.S. 

 Paris. 



Academy 0} Sciences, February 13. — M. Troost in the 

 chair. — On the existence of an ellipsoid of absorption in all 

 translucid crystals, even when without a plane of symmetry 

 or a principal axis : J. Boussinesq. — Study of the silicide 

 of carbon from the Canon Diablo meteorite: Henri Moissan, 

 In the residue left after dissolving a block of this meteorite 

 weighing 53 kilograms in hydrochloric acid, a hexagonal 

 crystal of silicon carbide was noticed. It was completely 

 identified by its appearance, density (32), and indifference 

 to most chemical reagents. Fused caustic potash gave 

 potassium silicate, and fused lead chromate, carbon dio.xide. 

 The origin of this block of iron may be terrestrial or 

 sidereal, but the existence of silicon carbide in the midst of 

 the metal shows that the products prepared with the elec- 

 tric furnace are met with in nature. — On soni.> constants of 

 pure methane, and on the action of solid methane on liquid 

 fluorine: H. Moissan and Chavanne (see p. 400). — The 

 eruptive basic rocks of French Guinea : A. Uacroix. 

 Besides biotite granite, numerous basic eruptive rocks have 

 been found in French Guinea, especially gabbros, peridot- 

 ites, and diabases, a detailed account of "which is given. 

 .\ttention is directed to the difference in the mode of weather- 

 ing in tropical and in temperate climates, as exemplified 

 in these samples. — On the use of photography as an aid to 



^'0. 1843, VOL. 71} 



topography : h. Laiaasedat. An account of an application 

 of the photographic method to the survey of the region 

 round Mount Argcie, in Cappadocia, on a scale of 1/80,000. 

 The use of photography has the advantage of reducing very 

 considerably the time required as compared with the 

 ordinary methods of surveying, and is especially advan- 

 tageous in mountainous regions. — Observations of the 

 Borrelly comet (1904 e) made with the Brunner equatorial 

 at the Observatory of Lyons: J. Guillaume. The apparent 

 position of the comet was measured on January 3, together 

 with the positions of two comparison stars. The comet 

 appeared as an object of the tenth magnitude, and possessed 

 a small nucleus. — Observations of the sun made at the 

 Observatory of Lyons with the 16-centimetre Brunner 

 equatorial during the fourth quarter of 1904 : J. Guil- 

 laume. The results are summarised in three tables giving 

 the number of spots, their distribution in latitude, and the 

 distribution of the facul^ in latitude. — Actinometric observ- 

 ations made at the summit of Mont Blanc : A. Hansky. 

 The observations were made in the observatory at the 

 summit of Mont Blanc with the instruments of M. Crova. 

 The conditions in 1900 were more favourable than in 1897 

 and 1898, and the results for this year are given in detail, 

 the most probable result for the constant being between 

 30 and 35. — On linear partial differential equations : M. 

 Hadamard. — On the deviation of falling bodies : Maurice 

 Fouche. .A reply to a criticism of M. de Sparre on a 

 former paper by the author. — The thickness of transparent 

 sheets of iron : L. Houllevigue. After trying unsuccess- 

 fully various methods for estimating the thickness of thin 

 films of iron, a colorimetric estimation with sulphocyanide 

 was found to give trustworthy results. The transparency (T) 

 of these films was determined before dissolving in acid for 

 the colorimetric test, and for films varying in thickness 

 from 0024 to 0056 milligram per square centimetre the 

 thickness was fouijd to be a linear function of log T. This 

 curve being established, the thickness of any given film 

 could be quickly determined by the photometer. — The auto- 

 matic registration of atmospheric ionisation : Charles 

 Nordmann. The charge introduced by the ions is removed 

 from the condenser plate by falling drops of water, the 

 constancy of flow being secured by a Marriotte's bottle. 

 The deviations of the electrometer in the arrangement 

 described, a diagram of which is given, are proportional 

 to the number of ions per unit volume of the gas. — On the 

 heat given off by paraffin submitted to the action of a 

 rotating electrostatic field of high frequency : Ch. Eug. 

 Guye and P. Denso. — On a new reaction of aldehydes and 

 the isomerism of their oxides : A. Conduche. The alde- 

 hyde is added to a dilute aqueous solution containing equi- 

 molecular proportions of hydroxylamine hydrochloride and 

 potassium cyanate. Well crystallised compounds separate 

 out, the melting points of which characterise the aldehyde. 

 The discussion of the composition of these compounds throws 

 light on the constitution of the isomeric aldoxinies. No 

 corresponding compounds are obtained when a ketone is 

 substituted for the aldehyde in the reaction. — The action of 

 hydrocyanic acid on epiethyline : M. Lespieau. The 

 nitrile C.H^.O.CH,— CH(OH)— CH,.CN is obtained in this 

 reaction, and the preparation and properties of several sub- 

 stances derived from this are described. — On the non-exist- 

 ence of two stereoisomeric ethyl dioximidobutyrates : L. 

 Bouveault and A. Wahl. The supposed existence of two 

 stereoisomers indicated by Hantzsch and bv Nussberger is 

 shown to be erroneous. — On the transformation of amylo- 

 cellulose into starch : Eugene Roux. — On the electrolysis of 

 organic acids by means of the alternating current : .Andr^ 

 Brochet and Joseph Petit. The electrolysis of formic and 

 oxalic acids can be easily effected with the alternating 

 current ; the results are the same as with the direct current, 

 but the yields are much higher. — On the phosphorescence 

 of phosphorus : E. Jungf leisch. It is shown that an inert 

 gas, saturated with the vapour of phosphorus, contains an 

 extremely small weight of phosphorus, the oxidation of 

 which gives rise to scarcely appreciable light effects. The 

 author regards his experiments as proving that a lower 

 volatile oxide is first produced, and that it is the oxidation of 

 this which gives rise to the luminous phenomena. — On 

 isodimorphism : Fr^d^ric Wallerant. — On the extension 

 of the alkaline rocks in the basin of .Aouache : H. Arsan- 

 daux. — Two species of Dalbergia in Madagascar produc- 



