“Now. 10, 1881] 
NATURE 
45 
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" The records of thunder and hailstorms in New South Wales 
up to the end of 1878 were examined by Mr. H. C. Russell, with 
reference to the risk from hail to the Exhibition Building erected 
in 1879. The list is given in this volume. Mr. Russell could 
not trace any period in those storms, except that they seemed 
“more numerous in the first year after a drought. They are not 
severe or numerous in wet years. The great number of storms 
when the earth is passing through the November meteor stream 
is noted. ; 
The so-called salt-bushes of Australia are known to have 
properties that are of great advantage to sheep, which relish and 
fatten on the food, especially in times of drought. Mr. Dixon 
has analysed some eight of those fodders of the Riverina district, 
and shows, by comparison with well-known European fodders, 
that they stand well as to nutritive value. One is struck with 
the extraordinary amount of ash. In seven of the eight, the 
average ratios of total ash, potash, and common salt to digestible 
matter (oil, carbohydrates, and albuminoids), taken as 100, are 
47, 9°538 and 7°689 respectively ; and the difference here from 
European fodders is conspicuous. Cotton bush (the eighth ex- 
amined) ranks with the latter. Only two contain a very large 
proportion of common salt, viz. oldman salt bush (the most 
prized by graziers), has 15°403, in the relation ju-t specified, and 
small salt bush, 14°590. While digestion is doubtless promoted 
by the soluble chlorides, it is in the wool that the greatest effect 
of the diet (so rich in potash) might be expected, and the high 
esteem in which Riverina wool is held, is a verification of this. 
Various kinds of coal of New South Wales have been sub- 
jected to analysis by Mr. Dixon and by Prof. Liversidge, the 
latter of whom specially wished to see how they compared with 
our coals, He found the Northern District coals to contain 
least ash, average percentage 4°61 ; those of the Western Dis- 
trict have 10°44 per cent, ; and those of the Southern 10'99. 
Thus some of the Northern coal is quite equal in this respect to 
the Welsh and Scotch coals, and but little inferior to the English 
Newcastle coal. The quantity of sulphur in New South Wales 
coal is by no means excessive. Prof. Liversidge also furnishes 
an account of some minerals from New Caledonia, including 
the nickel-bearing Vowmeaite. This mineral seems to be com- 
pletely amorphous; the masss_lits up into smooth concave-convex 
pieces like petals of an unopened bud. It is in some cases soft 
and brittle, and in others hard and tough enough to be cut into 
ornaments. ‘The colour varies from the palest tinge of green to 
full rich malachite green. The composition ranges from practi- 
cally pure hydrated silicate of magnesia to what is also practi- 
cally only hydrated silicate of nickel. The earthy cobalt ore 
(asbolite) from New Caledonia differs considerably from those 
met with in other places; baryta is entirely absent, but magnesia 
seems to have taken its place in some cases. 
An interesting paper by Dr. Manning, medical superintendent 
of the Hospital of the Insane at Gladesville, treats of the causes 
of insanity in 3077 patients admitted to that institution in ten 
years from 1869; a comparison being also drawn with English 
statistics. We note that 3°9 per cent. of the cases of insanity 
are attributed to isolation and nostalgia conjointly (a category 
not given in the English table). The cases of pure nostalgia 
were those of foreigners, who spoke English most imperfectly. 
The cases of isolation included shepherds, whose occupation 
some years ago was most lonely, and still is, in some places, 
though the state of things is improving in this respect. Dr. 
Manning found last year that more than one half (1038 out of 
2036) of the inmates of those institutions in the colony were 
apparently quite friendless, and that 10 per cent. were foreigners. 
The isolation, which is something terrible to a new emigrant, 
and which lasts often for years, is kept up by the disparity of 
the sexes, which at the close of 1879 stood at 409,665 males and 
324,617 females, and it is fostered by the peculiar shifting and 
restiess life of the miners and the bushmen, Dr. Manning thinks 
the insanity from intemperance has been exaggerated ; the per- 
centage at Gladesville is 8°3. The vile quality of the drink (he 
considers) and the system of drinking (short reckless outbursts, 
with prolonged periods of abstinence), are prominent factors in 
the result. Sunstroke, as might be supposed, causes insanity to 
a much greater extent in New South Wales than in England; 
5 per cent. of the cases are accredited to it. Dr. Manning also 
expresses the opinion that insanity through lactation prolonged 
beyond the ordinary time is more frequent. Again, he is struck 
with the number of cases admitted with symptoms of dyspepsia 
and ‘‘chronicill health,” and he attributes a considerable number 
of those to the want of varied and properly cooked meals. As 
to hereditary transmission of insanity, the Gladesville statistics 
give only 7'2 per cent., but they are much less complete than 
the English, owing to the difficulty of getting to know the family 
history. 
We can do no more than briefly indicate some of the other 
subjects dealt with in this volume; some new double stars, the 
longitude of Sydney Observatory, the opposition and magni- 
tudes of Uranus and Jupiter, the orbit elements of Comet I. 
1880, changes in the surface of Jupiter, catalogue of plants 
collected by Forrest in North-West Australia, fossil flora of 
Eastern Australia and Tasmania, piturie, iron acted on by sea- 
water, wood inclosed in basalt, fossils from Paleeozoic rocks of 
New South Wales, schemes of water supply for Sydney, wells 
in the Liverpool plains. 
ON THE APPLICATION OF PHOTOMETRY 
IN THE STUDY OF THE PHENOMENA OF 
DIFFUSION IN LIQUIDS 
§1. SINCE the publication in 1803 of Berthollet’s work,! in 
which it is already asserted that the diffusion of salt 
solutions in water takes place according to the same laws as the 
propagation of heat in solids, an exact method has frequently 
been sought for determining the coefficient of diffusion. The 
attempts in this direction have failed to give concordant results, 
which may best be judged from a compilation of the numbers 
expressible in absolute units with reference to chloride of sodium b 
whose coefficient of diffusion in water has most frequently been 
measured, The coefficient is stated to be— 
ByAGrahamyaoe Coane ee eS 
” 9° os mae) 105 2 
By Fick ... en; Ae 6 CTE a (oer pmcaed 
By Johannisjanz ... ... 53 | BEC. 
By Schuhmeister, at 10° C, ee 97 / 
When we inquire into the laws which govern this coefficient 
we meet with even greater discrepancies. Thus Graham, Fick, 
and Schuhmeister’s researches indicate the increase of the co- 
efficient with the rise of temperature. Johannisjanz finds no 
such relationship, Thus H. F. Weber, experimenting with 
sulphate of zinc, concludes that the coefficient of diffusion de- 
creases with increase of concentration. Schuhmeister asserts 
exactly the contrary. 
The importance which diffusion has gained of late as a means 
of investigating and solving -many problems connected with 
molecular physics? induced me to search for a method which 
should permit me to investigate the processes of diffusion, not 
alone with more accuracy than heretofore in that direction in 
which the final results may be ascertained by simple weighing, 
but also to open up a new field of research which has been inac- 
cessible up to now for want of suitable methods. A detailed 
description of my method, and a full account of all the circum- 
stances to be observed in carrying out the experiments, will be 
found in Wiedemann’s Annalen, vol. xiii. pp. 606-23. I will 
only give here the general outlines, 
In the middle of a large glass trough a glass dish is inverted. 
On the top of this dish a narrow but thick glass rod is placed 
horizontally, and upon this four cylindrical vessels of approxi- 
mately equal height at suitable distances from each other and 
from the walls of the trough, These are filled with solutions of 
the salt to be investigated, in such a way that the meniszus 
attains its maximum height. Water is now poured into the 
trough till it reaches in height o°r cm. below the edge of the 
shortest cylinder, and the whole allowed to stand for several 
hours to equalise the temperature. After this, by means of a 
specially constructed funnel, more water of exactly the same tem- 
perature as the water in the trough is introduced, until it reaches 
a height of several millimetres above the edge of the cylinders. 
The apparatus is now left to itself. 
To interrupt the experiment a method has been devised, the 
description of which will also be found in Wredemann’s 
Annalen. 
The result is calculated by the formula— 
p= I 
4 
“Essai de statique chimique,” 
2a? 
Ge Adal 
T Berthollet, 
409-429. : a : ae 
2 See Wroblewski, “‘On the Nature “of the Absorption of Gases,’’ in 
Nature, vol. xxi. p. 190. 
Paris, 1803, vol. i., pp- 
