1819] Scientific Intelligence. 467 
IX. Alloys of Platinum. By Mr. Fox. 
(To Dr, Thomson.) 
ESTEEMED FRIEND, Falmouth, Fourth Menth, 10, 1819. 
Although it be well known that platina readily forms alloys 
with many of the metals, | am not aware that the phenomena 
which attend its combination with some of them have ever been 
noticed ; and under this impression I shall briefly mention the 
result of some experiments I have recently made. 
If about equal bulks of platina and tin be heated to redness, 
in contact with each other, they will combine suddenly with 
great vehemence, and a very considerable extrication of light 
and heat, which will continue for some little time after their 
removal from the fire. 
This experiment may be easily tried with a blow-pipe, either 
by placing the metals together on charcoal, or enveloping them 
(or tin only) in platina foil, and exposing them to the flame from 
a blow-pipe at the end of some platina wire. The more effectually 
the free access of the air to the tin is prevented the better, as 
a very small degree of oxidation on the surface greatly diminishes 
the success and brilliancy of the experiment. When prepared 
in this manner, the flame of the candle alone, without a blow- 
pipe, is sufficient to fuse these metals, provided the quantity be 
not too great. 
The moment the combination commences, the whole is formed 
into a brilliant globule of fused metal; and the heat is so mtense 
that on my letting it drop into a basin of water, it continued a 
short time at a very high red heat under the water; and not only 
discoloured the part of the basin where it fell, but even imbedded 
itself in the glaze of the earthenware, so that it was not 
readily detached from it. 
The same phenomena were exhibited in the combination of 
platina with antimony. The latter alloy I exposed for:a consi- 
derable time to a high degree of heat, till it ceased to be ma 
state of fusion, in consequence of the sublimation of the anti- 
mony ; when, on being hammered, it proved to be malleable; in 
fact, very little besides pure platina remained. In this manner, 
I am of opinion, platina may be obtained, if not quite pure, at 
least sufficiently so for all the common purposes to which platina 
is applied, as it certainly will not be fused again at any heat 
under that which has been employed in making it. 
Zinc enveloped in platinum foil, so as to exclude the free 
access of the air, on being exposed to the flame from a blow- 
pipe, exploded with vivid combustion, and was wholly converted 
into the white oxide. Very little of the platina wasfused. _ 
I attribute the great heat excited by the combination of platina 
with tin and antinomy to the inferior capacity for heat of the 
alloy, though this, perhaps, does not fully explain the cause of 
the yery rapid combination os taken place. 
G 
