460 
combination. Such facts as these, if well established, render 
necessary some form of dissociation hypothesis. 
A Grotthus chain of quite eguidistant atoms might serve, 
instead of actual dissociation, or a momentary dissociation 
would be sufficient ; but no hypothesis which involves a tearing 
asunder of molecules in the zz¢erior of a homogeneous electro- ! 
lyte can be permitted. 
Herein lies the great distinction between electrolytes and 
dielectrics. 
Hypotheses (1) and (2) may be held in either of two forms : 
(a) The electrical influence of the electrodes may be supposed 
to reach every molecule of the fluid. This was Grotthus’s form 
of (1), and is Quincke’s form of (2). 
(6) The electrical influence of each electrode may only extend 
within molecular distance of its surface, while the adjustments 
occurring in the main body of the fluid are effected by ordinary 
diffusion. This was probably Faraday’s form of (1) and it is 
Maxwell’s form of (2). 
Helmholtz’s hypothesis (3) emphasises the (2) aspect of the 
matter by appealing to electrostatic interactions of the atoms to 
maintain uniformity of composition. And within a range of 
1o-® centimetres of each electrode there is supposed to exist an 
ordinary electrostatic strain, like that in an ordinary dielectric 
condenser plate. 
The great magnitude of the atomic charges explains the 
feebleness of the difference of potential required to effect de- 
composition on electrostatic principles. And the same thing 
suggests a mainly electrical theory of chemical affinity. 
To separate an atom from its charge requires expenditure of 
work, hence Helmholtz’s theory of a specific attraction between 
matter and electricity, which he uses to explain Volta’s 
“contact-force,”’ the charge of atoms in a molecule, frictional 
electricity, and many other phenomena. 
VI. Addenda. 
Calculation of EMF needed to effect decomposition— 
(a) of a dielectric, 
(4) of an electrolyte, 
on electrostatic principles. 
Suggested theory of disruptive discharge. 
Possible distinction between chemical 
molecular aggregates. 
Discussion of various phenomena from the point of view of a 
possible ‘‘atomic”’ theory of electricity. 
compounds and 
NOTES 
SINCE our last issue Dr. Harting, of the Dorpat Observatory, 
has announced an apparent variation in the great nebula of 
Andromeda, which has caused some excitement in the astrono- 
mical world. As represented in all our drawings, and, still 
better, in a photograph which Mr. Common was fortunate 
enough to obtain last year, the centre of the nebula appeared to 
be only moderately condensed. There was no star or stellar 
point. Now, on the contrary, there is a most unmistakable star 
of the eighth or ninth magnitude. The question is, is this a 
stella nova in the line of sight of the nebula, or has the pheno- 
menon been produced by a new condensation in the centre of 
the nebula itself? Opinion inclines to the latter view, as, ac- 
cording to some accounts, other accompanying changes have 
been seen with large instruments, &c. But, on the other hand, 
spectroscopic evidence that the apparent nebula is not a very 
distant cluster is absent. By our next issue we may hope for a 
large harvest of telescopic and spectroscopic observations of this 
new object. 
TuE International Congress of Schoolmasters was opened in 
the Grand Theatre at Havre on the afternoon of the 6th instant, 
Mr. Goblet, the Minister of Public Instruction, presiding. 
THE Severn tunnel has now been completed, and on Saturday 
last a train containing officials and their friends passed through 
it from end to end. 
A CASE of Asiatic cholera has occurred at Cardiff. A labourer, 
loading a vessel which had recently arrived from Barcelona, 
NATURE 
[ Sept. 10, 1885 
drank water which had been put into a cask at that port, and 
which was described by the medical inspector as totally unfit to 
drink, having the appearance of discoloured milk, and being 
putrid. The man died in a few hours of Asiatic cholera. 
On August 25 and subsequent days was held in Turin the 
International Congress of Alpine Clubs. The principal topic of 
discussion was the better management of refuges erected in 
different parts of the Alps, new regulations for guides, and 
pensions to be granted to them. The honorary president was 
the King of Italy, His Majesty being represented by M. Loyi ; 
the acting president was Prof. Ferrati. The readings of mini- 
mum and maximum thermometers were also collected and dis- 
cussed. Several excursions took place at the close of the 
session. 
THE German Meteorological Society met for its third congress 
at Munich last month. Prof. Bezold, of Munich, who delivered 
the address of the meeting, took for his subject ‘‘ The Advances 
of Meteorology during the last Ten Years,” dwelling mainly on 
the alterations made by the introduction of the synoptical method 
in connection with telegraphy. 
THE eleventh Audletin of the United States Geological Survey 
is a paper on the quaternary and recent mollusca of the Great 
Basin, with descriptions of new forms, by Mr. R. Ellsworth 
Call, with an introduction containing a sketch of the quaternary 
lakes of the Great Basin, by Mr. G. K. Gilbert. 
REPEATED severe shocks of earthquake have occurred in the 
south-east of Lower Austria and in the north of Styria, and have 
been followed by further shocks in Bonia, descriked as moving 
from east to west. 
WE have received Prof. Holden’s account of the progress of 
astronomy in 1884, and Prof. Rockwood’s account of vulcanology 
and seismology for the years 1883 and 1884, reprinted from the 
Smithsonian Report for 1884 ; also Mr. Albert Williams’s report 
on placer mines, and mining districts, from the report of the 
tenth census of the United States on the statistics and technology 
of the precious metals. 
THE programme of the technological examinations of the City 
and Guilds of London Institute for the Advancement of Technical 
Education for the session 1885-86 has been published. It con- 
tains a detailed syllabus of the examinations for the different 
grades on each subject, and copies of recent examination papers. 
It is to be obtained at the offices at Gresham College, and at 
Exhibition Road. 
Mr. G. J. Symons, who has examined the trees recently 
damaged by lightning in Richmond Park, has communicated 
the results of his observations to the Zzmes. They are two of a 
group of oaks in the eastern part of the park, slightly south-west 
of, but very near, the White Lodge. They were fine trees, 
their girth at 3 feet being 11 and 12 feet respectively ; the trunks 
are 23 feet apart, and one is nearly due north of the other. 
There are three other trees quite close to them (within 40 feet), 
which are uninjured, except by the branches which were thrown 
upon them. The injury to one tree, though fatal to it, is un- 
important, but the other tree affords a tremendous instance of 
disruptive power. It appears to have been cut through horizont- 
ally at about 3 feet above the ground ; the upper portion shows 
comparatively little injury, but the lower part is not merely 
stripped of its bark, but burst open in a very intense way ; 
spikes of the stem, several inches thick and ro to 15 feet long, 
, stand out from the trunk somewhat like the ribs of an umbrella 
before it is fully opened, and grip between themselves and the 
centre of the trunk branches which fell from the upper part 
before they had time to reclose, while the ground for perhaps 
200 feet around is strewn with the bark and fragments of 
