MR. GEORGE GORE ON FLUORIDE OF SILVER. 
o ;•» o 
odd 
The platinum boat was corroded and had lost 6-08 grains in weight. The total weight 
of the residue, including platinum in it, was 230-55 grains ; it showed no visible colour 
of chemically combined platinum. 5T7 grains of it, digested with a strong solution 
of iodide of potassium, left -03 grain of platinum. A second portion, weighing 49-06 
grains, digested with a hot solution of mercuric nitrate, left 2 - 99 grains of platinum 
in large fragments. A third portion, of 8-60 grains, exhausted of soluble matter by 
hot water, lost 1-53 grain (including a small amount of dissolved argentic iodide, see 
note ||, page 330); and the filtered liquid gave by precipitation 1-37 grain of argentic 
chloride, =31*80 grains of undecomposed fluoride (including a little iodide) in the whole 
of the residue : -04 grain of platinum was found in the clear filtered liquid. The inso- 
luble part of the 8-60 grains was a pale-yellow powder, easily fusible, and weighed 7-07 
grains ; by twice fusing it with an excess of pure alkaline carbonates, 3*23 grains of 
metallic silver, entirely soluble in dilute nitric acid (except -01 grain of platinum), was 
obtained, pure argentic iodide requiring 3-23 grains. The composition of the total 
saline residue was about as follows : — 
Iodide of silver . 
Fluoride of silver 
Metallic platinum . 
Combined platinum . 
Total 
grams. 
195-00 
30-72 
5-01 
1-07 
231-80 
1 repeated this experiment with perfectly pure iodine, passing the vapour of the iodine 
over 29-83 grains of the fluoride during four hours at a low red heat: similar results 
occurred. A colourless vapour was evolved. The saline residue appeared to contain 
traces of a red platinum salt. The gain of weight of the boat and its contents was 23-14 
grains =27’21 grains of the fluoride converted into iodide. By analysis, as in the last 
experiment, 4-22 grains of argentic chloride was obtained, =3-73 grains of undecomposed 
fluoride (this number is too high, for the reason already stated) ; the other ingredients 
were also similarly determined. The boat was slightly corroded and had lost -43 grain. 
Composition of Residue. 
Iodide of silver, about . 
Fluoride of silver, about 
Platinum . . . 
Total . 
grams. 
50-35 j 
2-62J : 
•43 
:52-97 
53-40 
It is evident that, in these experiments at a red heat, iodine expelled fluorine freely 
from argentic fluoride, either in a free state or united Avith some of the excess of iodine. 
Several other kinds of platinum apparatus besides those described were devised and 
employed for effecting the reaction of iodine with argentic fluoride, but were found less 
effective. 
