Marcu 11, 1897 | 
NATURE 
453 
addition, the diagram shows the inversion in intensities of the 
spark and arc lines in the spectrum of a relatively cool star— 
such as a-Orionis. 
The facts illustrated by the diagram indicate that the 
enhanced lines may be absent from the spectrum of a star, 
either on account of too low or too high a temperature. In the 
case of low temperature, however, iron is represented among the 
lines in the spectrum, but at the highest temperature all visible 
indications of its presence seem to have vanished. 
BELLATRIX 
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| SORIONIS 
This result affords a valuable confirmation of my view, that 
the arc spectrum of the metallic elements is produced by mole- 
cules of different complexities, and it also indicates that the 
temperature of the hottest stars is sufficient to produce simplifi- 
cations beyond those which have so far been produced in our 
laboratories. 
CAMBRIDGE. 
Philosophical Society, February 8.—Mr. F. Darwin, 
President, in the chair.—On the kathode rays, by Prof. J. J. 
Thomson. The experiments described in this paper were of 
two kinds: the first set were on the electric charges carried 
along the rays, the second on the deflection produced in these 
rays when they traversed a uniform magnetic field. In the ex- 
periments on the electrical effects produced by the rays, the 
kathode, a plane disc, was placed in a small side tube fused on 
to a large bulb; between this tube and the bulb there was a 
thick earth-connected metal disc with a slit in it; a pencil of 
kathode rays shot through this slit into the bulb. In the bulb 
on the side opposite to the slit there was an arrangement similar 
to that used by Perrin in his experiments on the charges carried 
by the kathode rays; it consisted of two cylinders, one inside 
the other ; the outer cylinder was connected with the earth, and 
the inner cylinder (which was insulated from the outer) was con- 
nected with one pair of quadrants of an electrometer. Slits 
were cut in the cylinder so that the kathode rays could pass 
through the slits into the inside of the inner cylinder. The 
cylinders were placed at a considerable distance from the direct 
line of the rays, so that unless the rays were deflected by a | 
magnet they did not enter the cylinder. The charge in the 
cylinder produced by each make and break of the coil was in- 
vestigated. Aslight charge was found to pass into the cylinder 
even when it was notin the direct line of the rays, due probably 
to a diffused charge sent out from the tube through the slit into 
: ‘1; this 4 
the bulb at each discharge of the coil; this charge was small | parallelogram of forces and the laws of motion; (4) Appli- 
it was generally negative, but at high exhaustions was fre- 
quently positive. When the rays were deflected by a magnet 
so as to pass inside the cylinder, the cylinder received a strong 
negative charge ; the charge was large as long as the phos- 
phorescent patch was stopped by the cylinder, small when by 
the motion of the magnet the patch was removed to one side or 
another of the cylinder. This experiment seems conclusively to 
show that there is a flow of negative electricity along the 
NO. 1428, VOL. 55] 
kathode rays. The following experiments show, however, that 
there must be something besides a stream of negatively electri- 
fied particles along the kathode rays. If the coil is kept running 
the negative charge in the cylinder does not increase indefinitely, 
it reaches a certain limit and then remains constant, though the 
kathode rays keep pouring into the cylinder ; and further, if the 
inner cylinder be charged negatively to begin with, then if this 
charge exceeds a certain amount, though the insulation is 
perfect when the rays are not playing upon the cylinder, yet as 
soon as the rays fall upon it some of the 
negative charge escapes. In the experiments 
on the magnetic deflection of the rays, the 
rays were produced in a side tube and sent 
into a large bell jar through a slit in a 
metallic plate. The bell jar was placed 
between two coils arranged as in a Helmholtz 
galvanometer so as to produce a uniform 
magnetic field. The rays in their course 
through the bell passed in front of a glass 
plate ruled into squares. A large number of 
photographs of the rays were taken in different 
gases and at various degrees of exhaustion. 
The following were some of the results ob- 
tained. The magnetic deflection of the kathode 
rays in air, hydrogen, carbonic acid gas and 
methyl iodide is the same provided the mean 
potential difference between the kathode and 
the anode is the same. Coming through the 
slit there are certain ‘‘ rays” which are not 
deflected by a magnet: these have little if 
any power of producing phosphorescence. 
The path of the rays for the first part of 
their course was very approximately circular. 
—On electricity in gases and the formation of 
clouds in charged gases, by J. S. Townsend. 
In the paper on this subject it is shown that 
the gases, given off when certain chemical 
actions are going on, have sometimes a very 
large electrostatic charge. The oxygen and hydrogen given 
off when a current is sent through a sulphuric acid electro- 
lyte carry with them a positive charge, and when these 
gases are prepared in a similar manner from a caustic potash 
cell they carry with them negative electricity. The gases 
have the property of retaining their electricity in a very 
striking manner, the fraction of the charge lost when the gas is 
bubbled through a liquid being very small. When put into 
vessels and shaken up with sulphuric acid, a large proportion 
of the electricity still remains in the gas. If a charged gas be 
left in a flask it loses its charge slowly, for after the space of two 
hours it is found that 4th of the original charge remains. These 
gases have the property of condensing a cloud when they get 
into a moist atmosphere, which can be completely removed by 
sulphuric acid. The whole process of bubbling through watex 
and forming a cloud and again bubbling through sulphuric acid 
and removing it can be gone through without losing more than 
21 per cent. of the original charge on the gas. The dry gas 
when it gets into the air of the room will form a perfectly stable 
cloud in the unsaturated atmosphere. These clouds are very 
heavy and are easily weighed, and it was found that the weight 
of the cloud is proportional to the charge ; but the proportionality 
changes with the sign of the charge, the cloud being much 
heavier in negative oxygen than in positive oxygen, the quantity 
of electricity being the same in each case. 
DUBLIN. 
Royal Dublin Society, January 20.—Dr. J. Joly, F.R.S.,. 
in the chair.—The Committee, consisting of Prof. W. J. Sollas, 
F.R.S., Mr. R. Lloyd Praeger, Dr. A. F. Dixon, and Mr. 
Alfred Delap, appointed by the Royal Dublin Society to investi- 
gate the recent bog-flow in Kerry, presented their report, which 
was communicated by Prof. W. J. Sollas. The report was 
illustrated by photographs taken on the spot by Dr. A. F. 
Dixon.—Mr. T. Preston made two communications: (2) The 
cations of a fundamental method in kinematics and dynamics. — 
Prof. Hartley, F.R.S., and Mr. Hugh Ramage exhibited 
specimens of photographs of spectra which illustrate the use of 
the spectrograph in the minute and accurate analysis of minerals 
and metallurgical products. 
February 17.—Prof. G. F. Fitzgerald, F.R.S., in the chair.— 
The following paper was read:—On the geology of Slieve 
