ME. GEOEGE GOEE ON ELUOEIDE OF SILVEE. 
241 
water. Heated about 3 inches of the outer end of the retort to gentle redness during 
seventy-six minutes. Allowed the apparatus to cool, and slightly opened the lower tap 
of the receiver (which was in an inclined position to prevent the mercury rising into 
contact with the boat) under the surface of a large and measured bulk (GOO cub. centims.) 
of mercury in a graduated glass vessel; great rarefaction was found, and about 315 cub. 
centims. of mercury rushed in during four or five minutes ; the bulk of gas which had 
disappeared was 326-37 cub. centims. ( = 15-236 grains of chlorine) when corrected for 
difference of pressure. 
The tap II was now closed, and the retort separated from the receiver ; the residuary 
gas had a strong odour of chlorine, filmed mercury powerfully, and fumed in the air ; 
the reaction was evidently not complete. The stout platinum boat had a large hole cor- 
roded in it, and with the stout sheet platinum surrounding it, and saline residue, showed 
an increase of 16-46 grains in weight. The weight of the salt alone could not be defi- 
nitely ascertained. The saline matter was red-brown, and contained much dissolved 
platinum ; traces of it (weighing -15 grain) were found upon the retort. It was a little 
deliquescent and contained a small quantity of undecomposed fluoride, but consisted 
nearly wholly of a double salt in which chloride of silver was united to tetrafluoride of 
platinum. After cleaning the apparatus the following losses of weight were found : — 
retort, 1*67 grain; sheet platinum, -64 grain; boat, 20 - 58 grains; total, 22-89 grains 
( = 16-754 grains of chlorine). This includes some particles of metallic platinum im- 
bedded in the salt. These results show that the chlorine was absorbed without liberating 
much (if any) fluorine, and that 1*67 grain of platinum had been transferred from the 
retort to the saline mass. 
Thinking that the platinum boat may have conduced to the formation of the double 
salt, I made another similar experiment, using, however, a boat of pure gold and 70-16 
grains of recently fused fluoride. In this experiment the outer end of the retort became 
concave (indicating rarefaction) long before the end of the heating process. On opening 
the apparatus under mercury powerful rarefaction was found, and 300 cub. centims. of 
mercury rapidly ran in, and more would have entered but was prevented. Much free 
chlorine was again found, the gas fumed in the air, and the retort and its contents had 
gained 16-20 grains in weight. The gold boat and sheet platinum were powerfully cor- 
roded where the saline matter touched them. The saline residue contained very little 
soluble matter. After cleaning the apparatus the losses of weight were as follows : — 
retort, 1-13 grain; sheet platinum, 14- 5 9 grains ; boat, 11-36 grains; total, 27 "08 grains. 
After dissolving the chloride of silver by aqueous ammonia, and the salts of gold and 
platinum by hydrochloric acid, 6-32 grains of fragments and dust of those metals was 
found, thereby reducing the total loss by corrosion to 20-76 grains. The general and 
numerical results of this experiment closely agree with those of the preceding one *. 
* A number of other experiments were also made with this apparatus, hut with its lower half composed of 
glass ; in each instance the glass was more or less corroded, and there was less rarefaction than with the receiver 
formed wholly of platinum ; I have not described the results obtained because of the interference produced by 
this corrosion. 
