Fuly 16, 1885] 
IN ARURIE 
263 
¥ 
1885 
No. of organisms in r c.c. of water 
Jan. Feb. March 
Chelsea cca» 88 8 Ay 23 as 10 
West Middlesex... 2 ae 16 ee 7 
Southwark  ... .:. 13 SS 26 Bey 24) 
Grand Junction ... 382 ue 57 as 28 
Eambeth)..---- .: 10 ec 5 of 69 
WWew River... ... 7 nde 7 ae 95 
East London ... ... 2 nr 39 eS 17 
enti epi scih cak. Wes 10 = 41 =e 9 
General Conclusions. —Of the substances experimented with 
only greensand, coke, animal charcoal, and spongy iron were 
found to wholly remove the micro-organisms from water filtering 
through them, and this power was in every case lost after the 
filters had been in operation for one month. With the exception 
of the animal charcoal, however, all these substances, even after 
being in action for one month, continued to remove a very con- 
siderable proportion of the organisms present in the unfiltered 
water, and in this respect coke and spongy iron occupy the first 
place. 
The results obtained by agitating water with various solid 
materials show that a very great reduction in the number of 
suspended organisms may be accomplished by this mode of 
treatment, and the complete removal of all organisms by agita- 
tion with coke is especially worthy of notice. 
Again, the results obtained with Clark’s process show that we 
possess in this simple and useful mode of treating water a means 
of greatly reducing the number of suspended organisms. 
Thus, although the production in large quantities of sterilised 
potable water is a matter of great difficulty, involving the con- 
tinual renewal of filtering materials, there are numerous and 
simple methods of treatment which secure a large reduction in 
the number of organisms present in water. 
Physical Society, June 27.—Prof. Guthrie, President, in 
the chair.—Dr. Ramsay, Messrs. T. Hands, F. W. Sanderson, 
W. A. Shenstone, and T. H. Nalder were elected Members of 
the Society.—The following communications were read :—On 
the specific refraction and dispersion of the alums, by Dr. J. H. 
Gladstone. The refraction, dispersion, and specific gravity of 
nineteen different alums in the crystalline form were published 
by M. Charles Soret, of Geneva, in the Comptes rendus for last 
November. These, together with some additional data from 
Soret, Topsée, and Christiansen, were employed by the author 
for comparison with certain experimental results of his own and 
of Kannonikof. In this way additional proof was obtained that 
a salt has the same specific refraction, whether it be crystallised 
or dissolved, and that the refraction equivalent of a compound 
body is the sum of the refraction equivalents of its components. 
The refraction equivalents of the alkalies in these alums are in 
the following ascending order—sodium, potassium, ammonium, 
rubidium, methylamine, calcium, and thallium ; and of the other 
metals—aluminium, chromium, and iron. This is in accordance 
with what was previously known, but Soret’s observations do 
not afford the means of determining the equivalents more accu- 
rately than before. The refraction equivalents of iridium and 
gallium were determined for the first time, giving respectively 
17°4 and 14°8. The specific dispersion of the same compounds, 
measured by the difference between the specific refractions for 
the lines A and C, was also examined. The differences of dis- 
persion are much greater comparatively than the differences of 
refraction. The order was also determined, but not the actual 
dispersion equivalents of the different elements.—On a form of 
standard Daniell cell, and its application for measuring large 
currents, by Dr. J. A. Fleming. The author first referred 
to the careful and thorough investigation of the circumstances 
affecting the electromotive force of Daniell’s and allied cells by 
Dr. Alder Wright. He then described a form of all that had 
been found most convenient and reliable in practice. It consists 
of a U-tube in the two limbs of which are the two solutions of 
sulphate of copper and sulphate of zinc of the same specific 
gravity. Electrodes consisting of freshly electro-deposited copper 
and pure zinc that has been twice distilled dip into the two 
limbs. The E.M.F. of this cell is 1*102, and the variation of 
E.M.F. with temperature is practically 7¢/.—On the phenome- 
non of molecular radiation in incandescent lamps, by Dr. J. A. 
Fleming. Some years ago Dr. Fleming had called attention to 
a phenomenon in incandescent lamps very analogous to that of 
discharge in high vacua observed by Mr. Crookes. The inner 
surface of the lamp-glass was sometimes found to be coated with 
a deposit of carbon, with the exception of a clear line marking 
the intersection of the glass with the plane of the loop, and being 
in fact a shadow of the loop apparently caused by an emission of 
matter from the terminals. Dr. Fleming has since found how 
to produce this appearance at pleasure by passing a very strong 
current momentarily through a lamp, and has succeeded in ob- 
taining similar deposits of various metals that had been used as 
terminals. These deposits show colours by transmitted light, 
and as a general result the author concludes that red metals such 
as gold and copper appear green by transmitted light, whereas 
white metals like silver and platinum appear brown, a conclu- 
sion which, however, was challenged by Capt. Abney in the 
discussion ensuing.—On problems in networks of conductors, 
by Dr. J. A. Fleming. —Lecture experiments on colour mixtures, 
by Capt. Abney. The apparatus employed by Capt. Abney is 
a modification of Maxwell’s colour-box: the spectrum, instead 
of being formed upon a screen, is received upon a convex lens 
which forms an image of the face of the prism upon a screen. 
If all the light from the prism falls upon the lens this 
image is colourless, but by interposing a screen with a slit 
in the spectrum close to the lens, so as only to allow 
light of a given colour to fall on the lens, the image 
appears coloured with that light. By using two or more slits 
different lights may be mixed in any required proportions.— 
On stream-lines of moving vortex-rings, by Prof. O. J. Lodge. 
The communication described a method of drawing vortex 
stream-lines, consisting in superposing uniform motion repre- 
sented by a series of parallel lines upon the lines of a stationary 
vortex as given by Sir W. Thomson in his memoir on vortex 
motion, and joining up the corners of the quadrangles so formed. 
This operation is very simple, and by its application a number 
of the more remarkable properties of vortex-rings may be ob- 
tained, the general analytical investigation of which involves 
mathematical methods of the highest order. Drawings were 
exhibited showing the nature and behaviour of a single vortex- 
ring moving with different velocities, a vortex-ring approaching 
a large distant obstacle, the chase of two unequal rings, and 
many other cases.—On the thermo-electric position of carbon, 
by Mr. J. Buchanan. It having been observed that the carbon 
filaments of incandescent lamps usually gave way at the negative 
end, experiments were instituted to find if the destruction 
could be due to the ‘‘ Peltier effect” causing a local generation 
of heat. Observations on a platinum-carbon thermo-couple 
showed that a generation of heat would result from a current 
passing from carbon to platinum, but the effect was too small to 
account for the observed phenomenon. It was found that a 
couple of carbon-iron rose considerably in E.M.F. by maintain- 
ing the hot joint for some time at 250° C.—On some further ex- 
periments with sulphur cells, by Mr. Shelford Bidwell. The 
paper contains (1) a description of a class of cells which give a 
constant voltaic current, the electrolyte consisting of a solid 
metallic sulphide ; (2) an explanation of the unilateral conduct- 
ivity exhibited by selenium and by sulphur cells ; and (3) a 
description of a cell which gives, as the result of passing a 
current through it, a current in the same direction as the primary 
current. 
EDINBURGH 
Mathematical Society, July 1o.—Mr. A. J. G. Barclay, 
president, in the chair.—Mr. R. E. Allardice gave an account 
of a paper by Mr. Charles Chree on physical applicatious of 
polar co-ordinates to the displacement of elastic solid and fluid 
bodies, and contributed some notes of his own on solid geometry. 
—Mr. J. S. Mackay submitted a paper by Mr. Robert J. Dallas 
on the method of orthogonal projection.—Mr. A. Y. Fraser, 
the hon. secretary, and Dr. Rennet, of Aberdeen, were ap- 
pointed by the Society to represent it at the ensuing meeting of 
the British Association.—The president, in his closing remarks, 
stated that the membership of the Society at the end of its first 
session was 58, at the end of its second 92, and now, at the end 
of its third, 147- 
PARIS 
Academy of Sciences, July 6.—M. Bouley, president, in 
the chair.—New methods for determining the absolute co- 
ordinates of the polar stars without the necessity of ascertaining 
the instrumental constants, by M. Loewy.—On the movement of 
a heavy revolving body fixed at a point in its axis, by M. G. 
Darboux.—On some new properties of the differential parameter 
of the second order for the functions of any number of inde- 
pendent variables, by M. Haton de la Goupilliére.—-A reply to 
