REPORT ON THE COMPOSITION OE OCEAN-WATER. 
67 
Then the nncorrected specific gravity of the sea-water S, taken with reference to 
water of 4° = 1, is calculated as follows : — 
T T * 
0 mr l °’ 
meaning the weight of water of 4°, equal in volume to the displacement of the plunger 
at t°, and 
In ascertaining the error in S, as arising from the neglecting of the weight of the 
displaced air, L 0 itself may he substituted for 4 L 0 , i.e., we may assume <S to be wanted 
instead of 4 S. 
In my experiments 4 L 0 was always taken from a table founded upon a special series of 
experiments made at a previous time, when the weight, 8, of 1 c.c. of air varied from 
IT 87 to 1*220 mgrms. Mean, S 0 = 1*203. 
In series I., with the strong sea-water, the experiments formed three groups, the 
values of 8 being 1*217, 1*213, and 1*217 respectively. Mean, 8 4 = 1*216. Now the 
values W 0 and W 4 in themselves are not liable to any vacuum correction, as water is in- 
compressible ; L 0 = (W) — W 0 ; L 3 =(W) — W 1 ; hence the corrected sp. gr. S 0 is 
a _ (W)-W 1 + 8 1 L 0 
^o- (W) _ Wo + g oV 
or dividing by (W) — W 0 = L 0 , above and below, 
C. _b +8 ' _S + S, 
S »- 1 + 8 , "1 + 8 / 
or with sufficient approximation — 
S 0 = S + Sj — SS 0 . 
The correction (arithmetically) becomes a maximum, when S 0 is at its maximum 
and 8 4 at its minimum. Taking, then, 1000 S 1 = 1*216 grm. and 1000 S 0 == 1*220 grm.. 
we have t 
S 0 = S — 0*000037, 
or, for 4 W= 1000 ; S 0 = S — 0*037. 
With the mean values for S 0 and 8 we obtain 
1000 S 0 — 1000 S= -0*020. 
* 3®, means tlie sp. gr. of pure water at t°. 
t Taking S = 1-0275. 
