324 
ME. GEOEGE GOEE ON FLUOEIDE OE SILVER 
To ascertain if platinum vessels were corroded by chlorine in contact with argentic 
chloride at a red heat, a stream of the washed and dried gas was passed during half an 
hour over 166*67 grains of that substance in a melted state mixed with 10*30 grains of 
platinum filings, in a platinum boat within a roll of platinum foil in a glass tube. A 
gain of weight of T04 grain took place ; a red-brown salt of platinum was formed ; the 
boat was corroded, and had lost more than 1*58 grain in weight. 
With regard to the behaviour of an aqueous solution of fluoride of silver with chlorine, 
Phipson states (Chemical News, vol. iv. p. 215), “ When a solution of fluoride of silver 
is decomposed by a current of chlorine gas, the chloride of silver precipitated contains 
fluorine, and does not blacken under the influence of the solar rays; when exposed to 
the light it becomes of a light-brown tint, which is permanent even in sunlight. In this 
experiment a large portion of fluorine remains dissolved in the liquid ; but it gradually 
decomposes the water, evolving large bubbles of oxygen gas, which appear to arise from 
the precipitate at the same time, and not before the glass becomes attacked by the 
hydrofluoric acid formed.” 
I passed an excess of chlorine through a dilute solution of argentic fluoride in a pla- 
tinum cup; chloride of silver was freely precipitated ; the mixture was then filtered in 
the dark, and boiled to expel the excess of chlorine ; the clear liquid contained no silver, 
it was acid to test-paper, had no bleaching-power, contained a little hydrochloric acid 
and also hydrofluoric acid, the latter being shown by its giving a precipitate with a solu- 
tion of chloride of barium. The silver chloride turned violet in daylight. 
In some of these experiments I employed a graduated Cooper’s receiver, A (fig. 8), 
177*8 millims. high, 22*22 millims. diameter, and 60 cub. centims. total 
capacity, constructed of platinum, provided with a tightly fitting cap B to 
close its lower end, and a small exit-pipe C at its upper end, with an accu- 
rately fitting plug D, perforated in the direction of the dotted lines so as to 
act as a tap. The cap B having been cemented on air-tight by means of 
paraffin, the receiver was filled with washed chlorine. The tap D was then 
closed, and the lower end of the receiver immersed in an aqueous solution 
of argentic fluoride, with the arm E beneath the surface of the liquid. 
Bather rapid absorption of the gas took place, which ceased after about 
six hours. After standing twenty hours the lower opening of the vessel 
was closed, and the upper one momentarily opened ; no odour of chlorine 
remained, and the vessel contained a gas which repeatedly and vigorously 
reinflamed a red-hot splint, it was therefore nearly pure oxygen. The 
bulk of this residuary gas was about 21*8 cub. centims. when corrected for 
difference of pressure*, the original volume of chlorine to the level of the 
arm E being about 52 cub. centims. A precipitate of chloride of silver was 
found freely in the vessel. In a second experiment I filled the same receiver with washed 
chlorine, introduced 20 grains of argentic fluoride, added 3*5 cub. centims. of distilled 
* It is probable that some atmospheric air entered unobserved. 
