306 ON THE OXIDATION OF AMMONIA IN SEA WATER. 
to contain ‘006 grm. NH, per 100 litres. After standing one night 
and six hours in daylight, however, it contained ‘002 grm. NH, per 
100 litres. The preceding experiments show that when Ulva is 
assimilating rapidly and oxygen is given off, the ammonia in sea 
water is very quickly reduced. The amount of carbonic acid gas, 
however, available for purposes of assimilation is not clear; from 
the “Challenger”? Reports there does not appear to be any free 
carbonic acid gas in sea water, and Algz, therefore, must depend 
upon that which is in a state of ‘loose’ chemical combination. 
An experiment was now made to test the rapidity of action of 
a current of air blown through the water. A current of air at the 
rate of 400 c.c. per minute was blown through sea water which 
contained— 
At the commencement °030 grm. NH, per 100 litres. 
After five hours 023 - % 
After twenty-six hours ‘013 ai a 
After fifty hours 008 Me if 
A second experiment gave similar results, and it appears, therefore, 
that the oxygen given off by Alge is very much more efficacious 
than that of the atmosphere, which is probably due to its being in 
the nascent condition. 
