216 Value of Native Geld, de. 
20. Third speciinen, 
Grains. 
Weighed in ait... 022... .ccccncnsess S94 20 
Weighed in water ......csssssceee 1753'S 
Difference .....cseccescveceseee LOS 79 
284°25 
108-75 xX 1000 = 2614:7 
There is but a trifling difference in the result of these 
experiments ; the mean of the different specific gravities may 
therefore safely be taken as the standard specific gravity 
of Gold-bearing Quartz. 
Sp. Gr. 
No. 15. 2607 
SG Ga 
pp» Lec 2623 
ey Let 2606°6 
a Le 2624°6 
90. 26147 
6| 157069 
26178 Mean Specific Gravity, 
Which agrees very nearly with that given in the Tables. 
(Sash sii 
(Ss) £ | 
when w is the quantity of quartz,—S specific gravity of native 
Gold as settled by experiment, 18300,—s the specific gravity 
of Quartz similarly determined, 2618,—c = 480—or the num- 
Adopting, then, the former expression % = 
ber of grains in an ounce,—f varying number from 18000 
to 7000. The following Table will show the deduction to 
be made for the impurities existing in Mount Alexander 
Gold when the specific gravity of the sample falls between 
the numbers in the Table, the scale of which is sufficiently 
