MR. GEORGE GORE ON FLUORIDE OF SILVER. 
OOI 
OOl 
Approximate Composition of the Saline Residue. 
Before expulsion of Fluorine and Iodine. 
= 6*74 
Loosely united fluorine . 
3-92 
Loosely united iodine 
2-82, 
AgF 
6-00 
Agl 
53-70 
Loss . 
•57 
Total . . . . 
67-01 
After expulsion of Fluorine and Iodine. 
AgF 
O 
6*00 
Agl ......... . 53-70 
Total 
59-70 
These numbers show some disagreements; but more accurate ones could not be obtained. 
In a second similar experiment with 35-98 grains of the fluoride, the results were gene- 
rally similar; the vapour expelled by fusing the residue extinguished red-hot charcoal. 
The residue, after expulsion of loosely united fluorine and iodine, weighed 63-62 grains, 
and doubtless consisted of 60-23 grains of iodide of silver and 3-48 grains of argentic 
fluoride. In a third experiment 57 -55 grains of iodine and 80-85 grains of fluoride 
were employed ; the results were again similar. The yellow residue weighed 137-28 
grains. Crystals of silicon heated to redness in the vapour expelled by melting the 
saline residue, were quickly corroded, but did not visibly incandesce. The sublimed 
iodine fumed strongly in the air. After expulsion of all the free iodine, the residue had 
lost 14-12 grains and weighed 123-16 grains = a gain of weight of 42-31 grains by the 
silver-salt =49-753 grains of fluoride decomposed = 49*753 grains of iodine combined 
= 7'443 grains of fluorine liberated. In a fourth experiment the argentic fluoride was 
in a thick layer at the bottom of the cup ; and after heating the substances to about 250' 
Fahr. during ten weeks, more than half the iodine and fluoride remained unchanged. 
From the results of these experiments, I conclude that iodine slowly displaces fluorine 
from argentic fluoride at temperatures between 200° and 500° Fahr., without corroding 
platinum vessels, and forms a loosely combined compound of 
fluorine, argentic iodide and iodine, from which the loosely 
combined fluorine and ineffective iodine are expelled at a red 
heat. 
As the results were somewhat interfered with by the forma- 
tion of fluoride of silicon, I employed instead of a glass bottle , 
a platinum one of the form A, fig. 9, 76-2 millims. deep, and I 
25-4 millims. diameter, provided with a hollow stopper (B) 
ground into it as air-tight as possible. 
Two platinum cups were placed inside the bottle, one within 
the other — the outer and deeper one containing 64-80 grains of 
pure and fused iodine, and the other 80-46 grains of recently 
fused fluoride. The bottle, with its stopper secured, was inverted its whole depth in 
mercury at about 200° to 250° Fahr. during thirty-six days and then cooled. On 
opening, its gaseous contents exhibited no tension; it was full of a vapour of an 
Fig. 9. 
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