NITROGEN IN RAIN AND SNOW. 
Second Paper. 
By Nicholas Knight. 
In the proceedings of the Iowa Academy of Science for 1911, we de- 
scribed a series of experiments to show the amount of nitrogen in rain 
and snow, which we carried on during the year 1910. The work de- 
scribed in this paper has to do with a series of experiments in the! same 
line during some months of 1911-12. During this period we collected 
twenty-seven samples altogether, fourteen of which were snow, and thir- 
teen were rain or rain and snow. There were sixty-nine inches of snow 
and about five inches of rain. 
We collected the samples in two enameled pans, each about twenty 
inches in diameter. The samples were contained in glass stoppered 
blottles until the determinations were made, and kept as free; as pos- 
sible from contamination. There was not always a sufficient amount of 
the sample available to make the chlorine test. Our method for the 
chlorine was to evaporate 500 c.e. of the sample to dryness on the water 
bath, then to dissolve the residue in 50 c.c. distilled water, .and titrate 
with tenth normal silver nitrate solution, using neutral potassium 
chromate solution as the indicator. 
The oceans are doubtless the source of the chlorine. The salt spray 
from the waves as they beat upon the shore is caught by the winds and 
borne to the interior of the continent. We found chlorine in each sample 
examined for it. 
In the experiments described in our previous paper, we determined 
the nitrates by reducing to ammonia with aluminum foil in alkaline 
solution. The nitrate determinations of the present paper were made 
by the phenolsulphonic method, which seems to give lower results than 
the reduction with nascent hydrogen. 
