464 Scientific Proceedings, Royal Dublin Society. 
Sea Water from Belfast Lough. (TVitrations by permanganate 
lc.c. = 1 cc. oxygen at N. T. P.) 
A. Blank experiment required, : : 5 es) G0: 
Oxygen determination required, . : 3 EGS) 5, 
168 ,, 
B. Blank experiment required, : : . 4°74 c.¢.4 
Oxygen determination required, . ; 5 B03. 5, 
ECO 
Dissolved oxygen = 1°695 c.c. (mean of above). 
Gasometric Analysis. 
200 c.c. of the water gave— Equivalent to, per litre— 
COTM ul aeccnn ae : : ; . 45°70 c.c. 
Os 6 | OOO 5, : : ‘ : 420 ONee 
Nee) Wt O10y FU Fes) aes th iar Pe ORO 
Potall 124 20 ee GO Omee 
Dissolved oxygen, per litre, by new process, . 5 HOY Ge: 
es a 5 by gasometric analysis, 4°50 ,, 
Difference, 5 6 OPBD 5, 
The two preceding results show that the method fails, to some 
extent, in the cases of sewage effluents and sea water, when per- 
manganate is used for the titrations. It was therefore decided to 
try bichromate instead, and to contrast the results obtained with 
it with those yielded by permanganate and by gasometric analysis 
respectively. 
Sea Water from Belfast Lough—filtered and saturated with air at 
19:5°C. (Titrations by permanganate 1 c.c. = 1 c.c. oxygen at 
nfs 105/125) 
Blank experiment required, 4 : ard 2 9erc: 
Oxygen determination required, . E 5 OPS G5 
icrcmee 
1 A new solution of ferrous sulphate was employed. 
