REPOET ON THE COMPOSITION OF OCEAN-WATER. 
9 
purposes), and by a series of very careful titrations had been found to saturate 53 grms. 
of pure carbonate of soda (Na 2 C0 3 ) per 1028 ’9 grms. 
4’6 c.c. of such acid were weighed, diluted to 80 c.c. with water, and precipitated by 
addition of 20 c.c. of the chloride of barium solution and 5 c.c. of 20 per cent, hydro- 
chloric acid, the modus operandi being in strict accordance with the one followed in the 
analysis of the Challenger samples. The results were as follows : — 
I. II. 
Weight of acid, ..... 4 - 7663 4-7465 
Weight of barium sulphate corrected for filter-ash, . 05437 05420 
Weight of sulphur tri-oxide per 5 grms. of standard acid, 0T9582 0T9600 
Mean, . . . 0-19583 
By titration with sodium carbonate, 0T9438 
The difference, 1'5 mgrms. = 0"0075 of the quantity to be determined, is very small, 
and, besides, lies in the right direction, because the acid must be presumed to have con- 
tained at least traces of alkaline sulphates. 
In the following trials 4 - 6 c.c. of standard acid in each case were weighed, diluted to 
80 c.c. with artificial sea- water, and the precipitation of the sulphuric acid effected in 
exactly the same way as before. 
Three blank experiments with 80 c.c. of “ sea-water,” gave only 1'2, 1 2, and 1"8 mgrms. 
for the amount of barium sulphate + ash ; I adopted the value 1*2 mgrms. Eleven trials 
with known weights, each equal to about 5 grms. of acid, diffused throughout 80 c.c. 
of “ sea-water” gave for the amount of 
Sulphur tri-oxide per 5 grms. of standard acid ( allowing for blank) 
0-19600, 0-19583, 0-19569, 0-19586, 0-19695, 0*19624, 0-19662, 0-19689, 0-19629, 
0-19538, 0-19612. 
Mean, ........ 0-19617 
By analysis of the pure acid, ...... 0T9583 
Excess, ....... 0-00034 
The individual sulphates of baryta in the Challenger analyses amounted to about 
135 mgrms. each; the correction, therefore, would amount to about — 0"2 mgrm., i.e., to 
little, if at all, more than the possible error in the ojDeration of weighing. I accordingly 
allowed the weights of sulphate of baryta, obtained as above explained, to stand 
wwcorrected for foreign salts carried down. 
Determination of the Lime and Magnesia. 
40 c.c. of sea- water were measured off and weighed. They were mixed with 0"5 c.c. 
of 20 per cent, hydrochloric acid, and boiled to expel the carbonic acid. After cooling 
there were added — first, 5 c.c. of 10 per cent, ammonia, then 15 c.c. of an oxalate of 
(PIIYS. CHEM. CHALL, EXP. PART I. 1884.) A 2 
III. 
4 ‘7445 grms. 
0-5409 ,, 
0-19569 „ 
