470 Scientific Proceedings, Royal Dublin Society. 
Serres 3.—Aerated Tap Water, with added Sodium Nitrite, 
equivalent to 0:0084 grains per gallon (or 0-012 parts per 
100,000) of Nitrous Nitrogen. 
Blank determination required, . : . 4900 c.c. KMnO, 
(2) Caygen z oss pmean L0:345000 ee 
(2) 5) 39 39 2°35 
Dissolved oxygen = 9-555 Cees 
Dissolved oxygen, per litre, = 7°68 c.c. 
Aerated Tap Water alone. 
Blank determination required, . : . 4°890 c.c. KMn0O, 
I) Oxygen ue ay ogy fe =) 2002 One HS 
(2) 99 » 99 2°34 
Dissolved oxygen = 2°565 c.c. 
Dissolved oxygen, per litre, = 7°71 c.c. 
From the above experiments, it appears that the process ceases 
to give accurate results when the quantity of nitrite corresponds 
with 0-1 grain per gallon of nitrous nitrogen (or about 0°14 parts 
per 100,000), but that when the quantity is only about one-tenth 
as much, no perceptible error is introduced. In all probability, 
the process would give sufficiently accurate results for all practical 
purposes in waters containing nitrous nitrogen up to 0°05 grains 
per gallon. 
In conclusion, we desire to express our thanks to Mr. John 
Hawthorne, B.A., for the valuable assistance he has rendered us 
in carrying out the above experiments on the effects of nitrites 
and nitrates. 
