236 S. W. Johnson on Nitrification. 
to evaporate away before the next was added. Over the vapor 
thus generated was held the mouth of a cold bottle untila 
y simply exposing a piece of filter paper for a sufficient 
time to the vapors arising from pure water heated to boiling 
and pouring a few drops of acidified iodid of potassium-starch- 
ened with the purest water, was allowed to dry at ordinary 
temperatures, in the open air or ina closed vessel. (Jour. fir 
= Bos writer’s opinion, serve to clear up the matter satisfac- 
y. , 
_Zabelin ascertained in the first place that the atmospheri¢ 
air contained too little ammonia to influence Nessler’s test, 
which is of extreme delicacy and which he constantly ernployed 
in his investigations, 
abelin operated in closed vessels, The apparatus he used 
consisted of two glass flasks, a larger and a smaller one, which 
were closed by corks and fitted with glass tubes, so that @ 
stream of air entering the larger vessel should bubble throug? 
water covering its bottom and thence passing into the smaller 
flask should stream through Nessler’s test, Nextly, he found 
that no ammonia and (by Price’s test) but doubtful traces of 
nitrous acid could be detected in the purest water when dis- 
— Seay a8 this ap tus, 
elin likewise showed that cellulose (clippings of filter 
paper or shreds of linen) yielded no poten ioN essler’s test 
vec peated ina current of air at temperatures of 120° 
Lastly, he found that when cellulose and pure water togethet 
