June 24, 1897] 



NATURE 



91 



— On the electrification of air by uranium and its compounds, 

 by Dr. J. C. Beattie. Experiments were de^ribed to test the 

 electric state of the air in the neighbourhood of metallic 

 uranium, or of other metals on which a salt of uranium had been 

 deposited, when these were charged to a positive or negative 

 potential. The method adopted was the electric filter method 

 of Kelvin, Maclean, Gait. It was found that the air drawn 

 away from the negative electrode of a Ruhmkorff inductorium, 

 or from the kathode of a Crookes' tube, or from the wire joining 

 the negative electrode of the coil to the kathode of the tube, was 

 always negative y electrified. On the other hand, the air drawn 

 from the neighbourhood of the positive electrode of the coil, or 

 from the anode of a Crookes' tube, or from the wire joining them, 

 was found to be positively electrified. This positive electrification 

 of the air was always less than the negative corresponding. 

 With uranium insulated in a metal cylinder and connected to 

 the terminal of a battery, while the cylinder and the other 

 terminal were connected to the case of a quadrant electrometer, 

 the air was electrified positively when the uranium was electri- 

 fied positively, and negatively when the uranium was electrified 

 negatively. With the metal cylinder insulated and joined to 

 one terminal of the battery, while the uranium still inside the 

 cylinder and the other battery terminal were connected to the 

 electrometer case, it was found that the air was negatively 

 electrified when the cylinder was positively electrified, and vice 

 versA. The negative electrification of the air was always less 

 than the corresponding positive electrification. Both attained a 

 maximum value when the difference of jxitential was between 

 10 and 20 volts per cm. of air space. The same results were 

 obtained when metals were covered with salts of uranium and 

 then charged to positive and negative potentials. Dr. Beattie 

 also read a note on this subject by Lord Kelvin. The following 

 is an abstract of the note : — The effective conductivity induced 

 in the air by the uranium influence is, of course, greatest in the 

 immediate neighbourhood of the uranium, but there is some- 

 thing of it throughout the enclosure. Hence it may be expected 

 that electricity of the same kind as that of the uranium will be 

 deposited in the air close around it, and electricity of the opposite 

 kind in the air near the enclosing metal surface. And the quantity 

 flowing from either the uranium or from the surrounding metal 

 per sq. cm. of its surface increases but little with increased 

 voltage when this exceeds 5 or lo volts per sq. cm. Hence, if 

 the dimensions and shapes of the uranium and of the surround- 

 ing metallic surface are such, that for small voltage, such as 10 

 or 20 volts, the electricity lodged in the air by discharge from 

 the uranium preponderates over that discharged from the sur- 

 rounding metal, the excess must come to a maximum and 

 diminish, may be even down to zero, with greater and greater 

 differences of potential ; and at potential differences still greater 

 the electricity lodged in the air from the outer metal may pre- 

 ponderate, and the electricity in the air drawn off and given to 

 the filter be of opposite sign to that of the uranium which was 

 found with the lower voltages. Provided the configurations ate 

 such, and the voltages are so moderate that disruptive discharge 

 does not intervene to any practically disturbing extent. — On 

 simple formulffi giving approximate values of the roots of the 

 Bessel function oforder n and its first derived function, in terms 

 of the roots of (say) ]^{x) — o, Jg'ix) = o, (11 even), or those 

 of J3(.r) = o, ]^{x)='o, (« oddK by Dr. W. Peddie. In 

 this paper were given simple expressions by means of which 

 the roots of ]„{x) = o, ]\„j^i)[x) = o can be obtained when 

 the roots of J,(.r) = o, J',p^.i)(x) = o. are known (p < »). 

 These expressions lend tliemselves readily to numerical cal- 

 culation, and give values of the roots which become more and 

 more neaily true as x increases. Even for the smaller roots, 

 beyond the first two, the values found are highly approximate 

 when « - p is not too great. 



Mathematical Society, June 11. — Mr. J. B. Clark, Vice- 

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

 superposition by the aid of dissection (continued), by Mr. R. F. 

 Muirhead ; on a method of studying displacement, by Mr. R. 

 F. Muirhead ; the isogonic centres of a triangle, by Dr. J. S. 

 Mackay. 



Dublin. 



Royal Dublin Society, March 24.— Prof. E. Percival 

 Wright in the chair. — A paper was presented by Mr. J. E.- 

 Duerden, of Kingston, Jamaica, on Jamaican Actiniaria (Part i. 

 Zoanthenj), being communicated through Prof. A. C. Haddon. 

 — Prof. W. J. Sollas, F.R.S., read a paper on an apparatus for 

 submarine observation. Samples of new colours with metallic 



NO. 1443, VOL. 56] 



lustre, mosaics and pavement, lent by the Vitreous Mosaic 

 Co., together with a collection of chemicals made by Harrington 

 Bros, for the glass, china, and enamel industries, and for 

 photography and electro-plating, were described by Prof. W. 

 Noel Hartley, F. R.S. — Prof. E. J. McWeeney gave a demon- 

 stration of the bacillus of the bubonic plague. 



April 21. — Prof. W. J. Sollas, F.R S., in the chair.— On the 

 possibility of boring and raising a portion of a goral reef from 

 a great depth, and on an apparatus for demonstrating the folding 

 of rocks due to lateral pressure, by Dr. J. Joly, F.R.S. — The 

 formation of humus, its action in the nitrification of ammonium 

 compounds, bv Mr. W. E. Adeney. 



May 19.— Prof. W. J. Sollas, F.R.S., in the chair.— Dr. J. 

 Joly, F. R.S., read a paper on the volume change of rocks 

 attending fusion. — Sir Howard Grubb, F. R.S., read some 

 notes on a recent paper by Prof. Hale, of Chicago, respecting 

 the relative merits of reflecting and refracting telescopes, (a) 

 when used for visual work, {d) when used for photographic 

 work. — Prof. D. J. Cunningham, F. R.S., made some observa- 

 tions on the Cape hunting dogs in the gardens of the Royal 

 Zoological Society, Dublin. 



Paris. 

 Academy of Sciences, June 14. — M. A. Chatin in the 

 chair. — Experimental verification of the theory of gradually 

 varied flow in open channels, by M. J. Boussinesq. — Fossil 

 forest of Calaniites Suckoioii. Specific identity of Calamites 

 Stickowii (Br. ), Cistii (Br. ), Schatizlarensis {St.), folios its (Gr. ), 

 Calatnocladiis parallelinervis (Gr. ), and Calatnostachys vul- 

 garis (Gr. ), by M. Grand 'Eury. In a fossil forest at Treuil, 

 the remains consist almost entirely of Cal. Suckowii, of which 

 Cal. Cistii formed the part above ground. — Application of the 

 method of Poinsot to non-Euclidian statics, by M. J. Andrade. 

 — Statics and the geometry of Lobatchefsky, by the same. — On 

 the calculation of the resistance of the air to a disc for a velocity 

 of twenty metres per second, by M. P. E. Touche. — On a 

 propelling system for boats, by M. Y. Le Guen. — On 

 the cosmic force curve, by M. Baraduc. — On isometric 

 surfaces, by 'M. A. Pellet. — On small periodic move- 

 ments of long-period systems, by M. P. Painleve. — 

 A mercury interrupter for large Ruhmkorff coils, by MM. E. 

 Ducretet and L. Lejeune. The contact-breaker described, a 

 figure of which is given, possesses the advantages of high 

 speed, and certainty of break, without the danger of the 

 alcohol igniting after long use. It admits of ready adjust- 

 ment of speed. — On the dynamics of homogeneous chemical 

 reactions, which take place with evolution or absorption of 

 heat, by M. Michel Petrovitch. — Contribution to the history of 

 the iodides of phosphorus, by M. A. Besson. Chemically 

 pure PI3 has been obtained by the action of dry HI upon 

 PCI3. It is completely decomposed by water without forming 

 either free iodine or a solid deposit. The solution of PI3 in 

 carbon bisulphide is completely decolorised when shaken with 

 an excess of mercury. The possible existence of an unstable 

 P3I4 is also indicated, the existence of which gives a prob- 

 able mechanism for the conversion of yellow into red phos- 

 phorus by iodine, the equations being P3I4 = P2I4 + P 

 (red), and P2i4 + P (white) - P3I4.— On a method of oxi- 

 dation and chlorination, by M. A. Villiers. The presence 

 of a trace of a manganese salt accelerates many oxida- 

 tions, as, for example, that of oxalic acid by a mixture 

 of hydrochloric and nitric acids. This action is comparable 

 with that of a ferment, and is of importance in vegetable 

 physiology. — Breaking up of the fundamental band of chloro- 

 phyll, by M. A. Etard. By reducing the concentration of a 

 carbon bisulphide solution of chlorophyll derived from Loliuiii 

 perenne, the large band 729-635 splits up into three. This 

 method of dilution, together with the superposition of two 

 spectra in the same field, serves to show minute difference'^ 

 existing between chlorophylls derived from various sources. — 

 On the oxidising action of manganous salts and on the 

 chemical constitution of the oxydases, by M. Gab. Bertrand. 

 The salts of manganese act as oxygen carriers to many organic 

 compounds. The results are given of the action of various 

 manganous salts upon hydroquinone in presence of air, and the 

 theory is developed that these salts are partially hydrolysed into 

 free acid and manganous oxide, that the latter takes 

 one atom of oxygen forming Mn0.j, and that the organic 

 compound is oxidised by the remaining half molecule of oxygen. 

 — Action of nickel upon ethylene. Synthesis of ethane, by MM. 



