G42 
MR, EDWARD MATTHEY ON THE LIQUATION 
Platinum and Rhodium. 
Much attention has lately been drawn to an alloy of pure platinum, with 10 per 
cent, of rhodium, which has become important from the excellent service it has 
rendered in the determination of high temperatures. The alloy of platinum with 
10 per cent, of rhodium is used with pure platinum as a thermo-couple, and it is, 
therefore, interesting to be able to set at rest any doubt which might arise as to this 
alloy being uniform in composition when melted and drawn into wire. 
For this purpose I prepared an alloy, J, of:— 
Platinum.90 per cent. 
Rhodium.10 ,, 
by fusing together in a lime furnace by the oxyhydrogen gas flame pure melted 
platinum with pure melted rhodium in the above proportions. 
About one and a half kilogs. of this alloy was made, and after three times melting 
and casting, the alloy was re-melted and poured into a lime sphere of two inches 
diameter. 
Upon cutting the sphere into hemispheres I found that a beautiful white malleable 
alloy was the result, with very slight evidence of shrinkage, care being taken to 
provide against this by an extra long gate or pour. 
The following are the proportions of platinum and rhodium found by analysis at the 
points indicated :— 
Alloy J. Platinum 
Rhodium 
Parts in 1000 : — 
Outside. 
Intermediate. 
Centre. 
Platinum. 
Rhodium. 
Platinum. 
Rhodium. 
Platinum. 
Rhodium. 
902 
99 
900 
95 
899 
97 
898' 
98 
894 
100 
904 
100 
904 
94 
902 
94 
892 
96 
Average . 899 6 
97-4 
900 parts. 
100 „ 
Maximum difference between centre and mean of outside:—Platinum ‘6 per thousand; Rhodium, '4 per 
thousand. 
