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POPULAK SCIENCE REVIEW. 
an}i;bing to do with the phenomenon of supersaturation, and described experi- 
ments in which supersaturated solutions of various salts were kept for hours 
in catharised vessels at a temperature of 10° F., without crystallisation 
taking place . — Scientific Opinion, March 17. 
The Life of Faraday . — In the Proceedings of the Poyal Society (No. 106) 
Dr. Bence Jones has written a very touching biography of Faraday. It 
differs from Dr. Tyndall’s sketch in being made up in great part of Faraday’s 
letters, and in being divided into chapters corresponding to each year of his 
life. 
An Electric Clock . — The following is the specification of a patent quite 
recently taken out by Mr. K. C. Eapier of Westminster. Two or more 
breaks are employed for the purpose of making simultaneous contact, the 
object being to secure certainty of action. In order to hang a pendulum, 
a bar of steel or other metal, with one edge turned up, is supported on a 
frame. The pendulum stem does not reach quite up to this bar, but is sus- 
pended on it by two cheeks or plates fastened to the sides of the stem of 
the pendulum. This bar is fitted with a stud or pin midway between the 
cheeks, and on this pin turns a friction roller which offers far less resistance 
to the working of the pendulum than any kind of dead collar would do. 
Hydrogen and Palladium . — Perhaps the greatest physico-chemical disco- 
very of the quarter is that by Professor Graham, of the undoubted metallic 
qualities of hydrogen. The Master of the Mint has demonstrated that hy- 
drogen when absorbed by palladium combines with it to form an alloy. The 
following account of one of the experiments lays the result before our readers, 
the hydrogen being termed hydrogenium. Expei'iment I. — The wire had been 
drawn from wielded palladium, and was hard and elastic. The diameter of 
the wire was 0-462 millimetres; its specific gravity was 12-38, as determined 
with care. The wire was twisted into a loop at each end, and the mark 
made near each loop. The loops were varnished, so as to limit absorption of 
gas by the wire to the measured length between the two marks. To 
straigliten the wire, one loop was fixed, and the other connected with a 
string passing over a pulley, and loaded with 1-5 kilogramme, a weight suf- 
ficient to straighten the wire without occasioning any undue strain. The 
wire was charged with hydrogen by making it the negative electrode of a 
small Bunsen’s battery, consisting of two cells, each of half a litre in capa- 
city. The positive electrode was a thick platinum wire placed side by aide 
with the palladium wire, and extending the whole length of the latter within 
a tall jar filled with dilute sulphuric acid. The palladium wire had, in 
consequence, hydrogen carried to its surface for a period of one and a- half 
hoiins. A longer exposure was found not to add sensibly to the charge of 
Iiydrogen acquired by the wire. The wire w'as again measured, and the 
incrfa.se in length noted. Finally, the wire being dried with a cloth, was 
divided at the marks, and the charged portion heated in a long narrow glass 
tube kept vacuous by a Sprengcl a.spirator. The whole occluded hydrogen 
was thus collected and measured ; its volume is reduced by calculation to 
Bar. 7<X) millims., and Therm. 0° C. The original length of the palladium 
wire exposed was (KXM II millims. (23-682 inche.s), and its weight 1-6832 
gnu. The wire received a charge of hydrogen amounting to 936 times its 
volume, measuring 128 cubic centims., and therefore weighing 0 01147 grm. 
