256 _ Scientific Intelligence. 
and interesting results, especially concerning the chloride of silver. 
Five grains of pure chloride of silver were put into a long test tube full 
of distilled water, and placed in the sunshine to darken, the powder 
being frequently moved, so that every part might be acted upon by the 
sun’s rays. It was found, even after an exposure of a few minutes, 
that the water contained chlorine ; (it became opaque on the addition 
of nitrate of silver ;) and this was gradually increased as the chloride 
darkened. ‘The darkening was continued for several hours, after which 
the solution was filtered to free it from chloride of silver, and nitrate 
of silver added to the filtered liquid; the chloride of silver precipitated, 
when collected and dried, weighed 1:4 grains on one occasion, 1 grain 
on another, and 1°5 grains on a third trial. From several other experi- 
ments on the chloride of silver, the author is inclined to believe that 
the first action of the solar rays is to liberate one half of the chlorine, 
which, moisture being present, is very readily replaced by oxygen. 
By the continued action of the exciting cause, the other proportional of 
the combined gaseous element is in like manner set free and replaced ; 
and we now have oxide of silver, which in a short time is decomposed 
under the so called actinic power of the solar rays, and hence we have 
eventually nearly pure metallic silver in a state of extremely fine 
division. oe 
2. Effect of Cold on the Afinities of Substances:—M. de MaresKa 
has shown that sulphuric acid at —80° C. (—112° F.) no longer red- 
dens tournesol, does not act upon the alkalies, the carbonates, iodide of 
potassium, nor chlorate of potassa. Phosphorus and arsenic react 
upon Jiquefied chlorine, surrounded by solid carbonic acid; and the 
same is true of ammonia. Bromine, iodine and sulphur, also, will com- 
bine with chlorine, though cooled to —80° C. or —90° C. Antimony 
in powder, put into liquid chlorine at —80° C. produces a disengagement 
of much heat and light; but there is no action, if the antimony be pre- 
viously cooled down, or if dry chlorine gas be brought into contact with 
antimony placed in a tube inserted in solid carbonic acid. Potassium 
and sodium afford other examples of the same character. 
3. Electric Currents produced by the Vibration of Wires and 
Metallic Rods; by W. Sutrivan, (Phil. Mag., October, 1845, p. 261.) 
Mr. Sullivan, in his experiments on the electrical effect of vibration, 
took a piece of No. 15 brass wire, soldered it to @ similar piece of 
iron wire, and stretched it over two uprights of a wooden frame, 
(about ‘18 inches apart,) so as to produce, when set in vibration, a 
musical note; the ends of this compound wire were then connect 
with an exceedingly delicate galvanometer ; when in vibration a slight 
deviation of the needle took place, the direction of the current being 
from the iron to the brass, as in a similar therino-electric circle. On 
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