92 Properties of Minerals. 
Now fill to the brim with water and balance again; the 
amount of weight added is equal to the weight of water 
in the bottle; note this weight, = A. Now pour out a 
few drops of water, and weigh again, noting the weight 
as before, = B. Next add the coarsely powdered min- 
eral until the water is again to the brim, and note the 
weight, = C. The first weight diminished by the second 
is equal to the weight of water poured out, = (A—B), 
and the third weight diminished by the second, is equal 
to the weight of the mineral, = (C—B); therefore, 
(C—B) + (A—B = the specific gravity sought. An 
example will best illustrate this: Suppose, after bal- 
ancing the empty bottle on the scales as described, then 
filled to the brim with water, it is found that on adding 
to the other end of the scales 22.523 gms. the scales are 
balanced. 
Then weight of water in bottle..........—25.528 gms—A 
Wt. of water after pouring out a few drops=20.529 “ =—B 
Therefore, the weight of water poured out— 1.964 “ —A—B 
After filling to the brim with ore, weight—28.808 “ —C 
Subtract weight of water after pouring 
out a few drops, or ................-.= 20,558 “ =B 
Then the weight of ore in flask........... = §.249 “« —=C--B 
Now since the wt. of ore (5.249) divided by the wt. 
of its equal volume of water (1.964) is the specific grav- 
ity of the ore, we have: 5.249 + 1.964 = 2.672 =G. = 
[ (C—B) + (A—B) ]. Therefore, 2.672 is the specific 
gravity sought. 
Another method of determining specific gravities is — 
to suspend the. lump of mineral from a silk thread; 
. weighing first in the air. This wt. is called A. The 
mineral is then suspended and weighed emersed in wa- 
ter. This wt. is called B, and (A—B) is called C. Then 
A + C= G, = the specific gravity sought. 
. - 2 ag 
