F. H. Storer — Scheenbein’s Test for Nitrates. 189 
of the iron wire. When cold, the liquids were transferred to 
reelain capsules, mixed with iodo-zine-starch and acid, an 
eft to stand over night. Decided reactions were obtained in 
both instances, but the liquid to which the nitrate had been » 
added was deeper colored than the other, and the difference in 
tint between the contents of the two dishes seemed to be rather 
more marked than was the case in similar experiments where 
cadmium or zinc had been used instead of iron. It is not un- 
likely that iron would have been rather better fitted than either 
of these metals, for use in testing for nitrates according to the 
old plan. 
On repeating this last experiment with metallic lead, instead 
of iron, decided reactions were obtained with the iodo-starch in 
both dishes; but the colorations were of about the same depth 
as those ordinarily obtained with cadmium, and that obtained 
from the nitrate solution was no stronger than that from the 
pure water. 
Solutions of nitrate of potash (0:01 grm. N,O, to 100¢. c. 
water), made alkaline with potash or with lime, were reduced, 
with formation of some nitrite, when boiled for five minutes 
upon iron, or left to stand over night in contact with the metal 
in the cold; but the reactions with iodo-starch that were ob- 
tained in this way were less strong than those got by operating 
upon neutral solutions of the nitrate. 
The following substances failed to reduce nitrate of potash 
when boiled for five minutes with neutral solutions of that sub- 
Stance, containing 0-025 grm. N,O, in 100 c. ¢. water, or, at the 
least, no reaction could be obtained with the iodo-starch after 
pi ee phosphorus, glucose, or ferrous melee 
en i = © : 5 tas 
Was a ution that had been mixed with hydrate of po 
Pp tated ide, boiled 
“en five minutes with neutral, acid, and alkaline solutions of 
trate of potash (0-01 N ,0, in 100 c.¢. water), reduced some 
tne nitrate in each instance, so that reactions were obtained 
m adding iodo-starch to the several socio as the reac- 
ens were not very strong there seemed to be little encourage- 
—e proceed with the inquiry. 
If it were less difficult than it is, to manipulate with thor- 
ugly boiled water so that no atmospheric air should come 
