FrBruary 18, 1904] 
NAT ORE 383 
that the light arises from the association of ions, and has 
its origin in the positive ions, which in elements having 
diatomic molecules probably have not the same constitution 
as those molecules, but in elements with monatomic 
molecules may, when deionised, at once reproduce such 
molecules. The kathode glow the author ascribes to 
fluorescence, the gas acting as a screen to the kathode rays, 
and its molecules responding to the stimulus without being 
themselves permanently affected. This opinion rests on the 
way in which the glow maps out the course of the kathode 
rays, and on the observation that the spectral lines of the 
glow are in most cases reversible, and therefore probably 
have their origin in unaltered molecules of the several gases. 
In conclusion, the study of the kathode glow suggests that 
the solar chromosphere and corona are a huge kathode 
glow.—On a soluble colloidal form of ferric and of other 
phosphates: W. J. Sell, F.R.S.—On the distribution and 
spectra of metallic vapours in electric sparks: H. Ramage. 
—On the variation with wave-length of the double refrac- 
tion in strained glass: L. N. G. Filon.—On the reflection 
of sound: Rev. H. J. Sharpe. 
February 1.—Dr. Baker, president, in the chair.—Free- 
living fresh-water New Zealand nematodes: N. A. Cobb. 
Four new species, all belonging to known genera, are de- 
scribed. The specimens were dredged from the lakes, at 
depths ranging from 200 feet to 1150 feet.—Some High 
Andine and Antarctic Umbelliferee: A. W. Hill. The com- 
munication dealt with the genera Crantzia (Nutt.) and 
Azorella (Lmk.), which are widely distributed in the 
southern hemisphere.—On the relative amount of ionisation 
produced in air and hydrogen by Rontgen rays: R. K. 
McClung. The object of the experiments described in 
this paper was to determine, if possible, the cause of the 
great discrepancy which exists between the results obtained 
by various experimenters who have previously worked on 
this subject. The results obtained by the various investi- 
gators differ very widely from one another. Experiments 
were made with various Réntgen ray bulbs in order to see 
whether the source of the rays had any influence upon the 
relative amounts of ionisation, and it was found that the 
source of the rays influenced the result to a very marked 
degree. Quite large variations in the ratio of the ionisation 
in hydrogen to that in air were obtained according to the 
bulb used. As different bulbs, of course, give out rays of 
different quality, it is evident from the experiments that 
the ionisation in hydrogen as compared with that in air 
depends upon the type of rays used. Further experiments 
are at present in progress to determine to what extent this 
variation depends upon the state of the vacuum in the 
Rontgen ray bulb. These experiments are as yet quite in- 
complete, but the indications are that the relative ionisation 
in the two gases does depend to some extent on the pressure 
of the gas in the bulb. Further experiments are to be made 
on this subject. 
DvuBLIN 
Royal Dublin Society, January 19.—Mr. S. Geoghegan 
in the chair.—Prof. A. W. Conway read a paper on the 
reflection of electric waves from a moving plane conductor. 
—Prof. J. A. McClelland read two papers, (1) on the 
emanation given off by radium, (2) the comparison of 
capacities in electrical work (an application of radio-active 
substances). The first of these two papers contains an 
account of experiments made to test whether the emanation 
given off by radium is charged or not. The emanation is 
carried into a partially exhausted vessel by a current of 
air, the vessel being insulated and joined to a sensitive 
electrometer. No charge was detected. The ionisation pro- 
duced in the vessel by the emanation is measured, and it is 
shown that if each emanation particle had a charge equal 
to or greater than the charge on the gaseous ion, a 
measurable deflection must have been observed, otherwise 
the ionisation produced by each emanation particle must 
have been greater than what is possible. The conclusion is 
therefore that the emanation is not charged. The substance 
of the second paper is as follows:—A very steady current 
can be obtained between two plates, one of which is kept 
at a high potential, by placing between the plates a quantity 
of uranium nitrate. This small steady current is used to 
charge the capacities to be compared to a given potential 
measured by an electrometer, and the time of charging is 
NO. 1790, VOL. 69] 
accurately measured in each case. The two capacities are 
therefore compared by simply observing two intervals of 
time. Numbers are given to show the accuracy of the 
method and the wide range of capacities to which it is 
applicable. In particular it is shown that capacities as 
small as one micro-microforad can easily be detected and 
measured by this method.—Prof. G. A. J. Cole communicated 
a paper by Mr. J. R. Kilroe on soil separations by the 
centrifugal method. 
Paris. 
Academy of Sciences, February $.—M. Mascart in the 
chair.—The general law of distribution of rays in band 
spectra: H. Destandres. Since the spectra obtained with 
a concave grating are too feeble for the purpose of verify- 
ing the author’s hypotheses, he has used a plane grating 
with an astronomical mirror of silvered glass of 2-5 metres 
focal distance. This arrangement has given all the bands 
of the second group of nitrogen excellently defined. The 
law of distribution deduced is that, in general, each band, 
expressed in vibration numbers, is divisible into series of 
connected rays, each series being such that the successive 
intervals are in arithmetical progression.—A new electrical 
device for extinguishing the high frequency arc: M. 
d’Arsonval. In the production of high frequency currents 
for therapeutical use it is necessary to prevent the form- 
ation of an arc between the spark gap. By the use of a 
subsidiary condenser this result is obtained very simply.— 
Protective arrangements for electrical machines supplying 
high frequency generators: MM. d’Arsonval and Gaiffe. 
Numerous cases of breakdown of transformers and coils 
used in the production of high frequency currents are 
common, and one possible cause of this is the return of 
waves from the spark gap to the transformer. An arrange- 
ment of condensers and resistances is described by which 
this effect is stopped without any loss of power.—The action 
of phenyl-magnesium bromide upon anthraquinone. Sym- 
metrical y-dihydroxyl-y-diphenyl-dihydro-anthracene: A. 
Halter and A. Guyet. Anthraquinone reacts in the normal 
manner with the phenyl magnesium compound, but the 
yield of the carbinol is poor, on account of the slight solu- 
bility of the ketone in ether.—On the mechanism of the 
transmission of the n-rays through wires of different sub- 
stances: E. Bichat. The transmission of the n-rays by a 
wire is regarded as being analogous to the experiment in 
which light is transmitted from. one end to the other of a 
curved glass tube, by successive reflections. In support of 
this view, experiments on wires of different materials show 
that the transmission only takes place if the material of 
the wire is transparent for these rays. Thus the effect is 
not produced by a wire of lead, but the rays are 
transmitted by wires of copper, aluminium and zinc, 
all of which have been shown to allow of the passage 
of the n-rays.—On the determination of the displace- 
ment of a battleship: J. A. Normand.—On the true 
value of the major axis of a cometary orbit when 
far removed from the sun, and the supposed hyberbolic 
character of the comet 1890 II. : Louis Fabry. The author 
interprets the calculations of M. Strémgren as leading to 
an elliptical orbit for the comet 1890 IJ.—Remarks on 
differential equations of which the general integral is an 
entire function : Emile Borel.—On certain 6-functions, and 
on some hyperelliptic surfaces to which they lead: M. 
Traynard.—On entire series with entire coefficients: M. 
Fatou.—On the zeros of a class of multiferm  trans- 
cendentals : Georges Remoundes.—On the flame spectra 
of the alkaline metals: C. de Watteville. Photographs of 
the spectra of lithium, sodium, and potassium show that 
the rays fall into two groups, those which are equally 
strong in all parts of the flame, and those which are more 
intense in the lower part of the flame, that is to say, in 
that portion which emits the Swan spectrum. It is found 
that the rays in the former class are those which belong 
to the principal series of the element considered, whilst those 
of the second group belong to the secondary series of rays. 
The differences of the spectra would appear to be due to 
thermal causes only.—On the function which represents the 
magnification of objects seen through a transparent cone: 
C. Chabrié.—On the magnetic effect of convection 
currents: C. Gutton. By means of the increase of 
luminosity of a phosphorescent screen it is possible to 
