aay. Oy) J. MILNE CURRAN. 
of diamonds tested gave a higher specific gravity for our 
diamonds than the recorded specific gravities of South African 
or Brazilian diamonds. I picked about two grams of the best 
‘Bingara stones, and taking the average of two experiments I found 
Bingara diamonds, specific gravity at 60° F. 3-578. The highest 
specific gravity recorded by Dana for the-diamond is 3:525.! 
*Messrs. Etheridge and Davies in their report on New South 
Wales diamonds? quote the specific gravity of diamonds from many 
parts of the world, giving Mr. Harry Emmanuel’s work and that 
of M. M. Jacob and Chatrain as their authority. I reproduce 
their table, adding for comparison, the specitic gravity of some 
stones collected by myself. 
Hoe Cantey, | White Stones. | Yellow Stones. _ 
India sau a 3'524 3°556 
Brazil : 3°442 3-420 
Cape 3-520 
Borneo 3-492 
Bingara, parcel of 19 grams in the author’s collection 3°565. 
There is therefore some foundation for the generally received 
opinion that the refractive and dispersive power of Bingara 
diamonds is high. 
*For the last few years I have been using Bingara diamonds in 
my laboratory for charging the thin discs used in slitting rocks 
for microscopical study. In crushing the stones, the comparative 
absence of cleavage, and the dark colour of the powdered diamond 
are characters that attract attention. It has often been noted 
that the streak of the diamond is of a grey colour, while that of 
*1 7 have recently sent a small parcel of diamonds, weighing about it 6 
grams to Mr. F. B. Guthrie, rv.c.s., Acting Professor of Chemistry at the 
Sydnee University, with the request that he would determine the specific 
gravity of the parcel. He finds the specific gravity of these diamonds to 
be (mean of two determinations) 3565. These stones are from Bingara. 
Mr. Guthrie’s determination taken in connection with the figures above 
leaves no doubt as to the higher density of the Bingara gems. 
*2 Annual Report of the Department of Mines N. S. Wales, 1886, p. 42- 
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