OF METALS OF THE PLATINUM GROUP. 
633 
method which will be described subsequently ; the platinum will of course be the 
difference. 
D. Gold 
100 parts. 
Platinum 
900 
1 J 
Parts of gold in 1000 :— 
Outside. 
Intermediate. 
Centre. 
96T 
97-3 
93 
99-1 
97-9 
100-6 
101-8 
102 
Average . 99'9 
Maximum difference in the gold between centre and mean of outside, G'9 per thousand. 
D. 
To follow this up : an alloy of gold twenty-five per cent, and of platinum seventy- 
five per cent, was then made in a similar manner to the alloy D, and the utmost care 
was taken to ensure a thorough mixture of the two metals. This alloy was also 
melted in a lime furnace by the oxyhydrogen flame and cast into a spherical lime 
mould. The sphere weighed between 5 and 6 kilogs., and the alloy was hard and 
brittle, resembling somewhat one of grey cast-iron. 
The following are the results obtained from the hemispheres into which the sphere 
was divided :— 
4 M 
mdcccxcii. —A. 
