330 
MR. GEORGE GORE ON ELITORIDE OE SILVER. 
argentic fluoride * * * § , and the two cups placed in a glass bottle, the air of which had been 
dried by a stick of caustic potash f. The bottle, with its stopper well secured, was in- 
verted in mercury, with the mouth of the larger cup upwards, and kept at a temperature 
of 150° to 200° Fahr. during eight days. A small leakage of air took place during the 
first hour. The bottle was further heated during three weeks to a temperature between 
200° and 300° Fahr., and was then somewhat corroded. After a third heating to be- 
tween 300° and 450° Fahr. during two more weeks, until the colour of iodine had entirely 
disappeared, and during one day more, the corrosion was rather considerable J, and no 
mercury had entered the bottle. On opening the bottle under mercury, no contraction 
or rarefaction was found, and the bottle contained some fluoride of silicon; 3*53 grains 
of alkaline silico-fluoride was scraped off the bottle. The two cups (and their contents) 
had lost '58 grain in weight and were not corroded. On heating them to low redness 
in a long platinum tube retort provided with a long exit-tube, the outer end of the re- 
tort being kept cold, a boiling sound occurred and iodine sublimed freely ; tetrafluoride 
of silicon also escaped and deposited silica around the orifice ; the loss of weight, including 
only a small portion of the free iodine, was 3'44 grains. No signs were observed of a 
condensed liquid. By further careful heating of the whole retort, 3' 30 grains of free 
iodine (apparently containing some fuming vapour) was expelled, and a small amount 
of argentic iodide sublimed. I rubbed 22*89 grains of the very easily fusible residue to 
fine powder in plenty of boiling water § until all soluble silver-salt was extracted, and 
precipitated the filtered solution; 3'00 grains of argentic chloride was obtained =6*909 
grains of argentic fluoride [|, in the total 59*70 grains of saline residue freed from excess 
of iodine. If we assume 6*0 grains of unchanged fluoride of silver to have been present 
in the fused residue after expulsion of the free iodine, and the original fused silver fluo- 
ride to have contained 6 per cent, of free silver, the results may be approximately ex- 
plained thus: — 2*41 grains of iodine united with the 2*05 grains of free silver to form 
4*46 grains of Agl ; 26*21 grains of iodine decomposed 26*21 grains of AgF, forming 
48*5 grains of AgT, and took the place of 3*92 grains of fluorine, only a small portion of 
which was expelled by the heat employed to effect the reaction. 
* The fluoride probably contained about 6 per cent, of free silver. 
t It was absolutely necessary in these experiments to exclude the least trace of moisture ; otherwise the iodine 
was rapidly absorbed. 
+ It is astonishing how much corrosion of glass the most minute amount of watery vapour will under such 
circumstances produce ; the moisture probably acts in such a way that a series of chemical reactions take place, 
attended by continued reproduction of a portion of water. 
§ A mixture of argentic iodide and fluoride melts to a thin black oily looking liquid under a small quantity 
of boiling water. 
|1 This number is too great ; I have found by experiment that iodide of silver dissolves in a strong aqueous 
solution of argentic fluoride, and is reprecipitated on diluting the liquid. 
