Lerts anp BLraxe—Estimation of Oxygen in Solution. 469 
But the amount of nitrites which may be found in water or 
sewage effluents is usually minute, and the question therefore 
which we had to decide was whether such quantities would appre- 
ciably interfere with the accuracy of the process. 
The experiments were made in the same way as with the 
nitrates, with the following results :— 
Series 1.—Aerated Tap Water, with added Sodium Nitrite, 
equivalent to 1 grain of Nitrous Nitrogen per gallon. 
Blank experiment required, 3 >) dgollicres en; 
Oxygen determination required, . . 4°20 
93 ? 
Dissolved oxygen = 3°81 c.c. 
Dissolved oxygen, per litre, 5 = O96 Ge: 
Aerated Tap Water alone. 
Blank experiment required, : . 4°70 c.c. KMn0, 
Oxygen determination required, . 5 ROD 
99 99 
Dissolved oxygen = 2°48 c.c. 
Dissolved oxygen, per litre, : = PHS) Ose 
Series 2.—Aerated Tap Water, with added Sodium Nitrite, 
equivalent to 0-1 grain Nitrous Nitrogen per gallon. 
5 Blank experiment required, . Ae mean = 5'135 c.c. KMn0, 
9? 9? 9 . 
(1) Oxygen determination required, 2°53 
2? 
} mean = 2535 ,, 
(2) 2) Pr) rr) 2°04 
Dissolved oxygen = 2°600 c.c. 
Dissolved oxygen, per litre, = 7:82 c.c. 
Aerated Tap Water alone. 
e Blank experiment required, . ego tment = 4-695 c.c. KMn0, 
?) 99 99 * 
(1) Oxygen determination required, 2°21 Bee ee Waco tg 
(2), Be ones aw 
Dissolved oxygen = 2°485 c.c. 
Dissolved oxygen, per litre, = 7°47 
SCIENT. PROC. R.D.S., VOL. IX., PART IV. 2M 
