DETECTION OF ADULTERATION 57 
older tests. A solution is made by dissolving 
0.035 gram pure morphin sulfate in 10 c.c. of 
sulfuric acid. This solution does not keep well. 
A convenient amount of the sample is placed in 
a dish or beaker, a watch-glass containing 1 c.c. 
of the above solution is floated on it, and the dish 
covered with a glass plate. The materials are 
allowed to remain undisturbed at room-tempera- 
ture for several hours. Formaldehyde is in- 
dicated by the development of a color ranging 
from pink to dark blue. A black discoloration 
is disregarded. Bonnet found that with 1 part 
of formaldehyde to 25,000 parts of sample a 
distinct color appeared in one hour. 
In testing ice-cream and similar articles it 
must be borne in mind that some of the flavor- 
ing materials being aldehydic in nature may 
simulate formaldehyde. La Wall has found 
that vanillin may act thus. The phenylhydrazin 
and Bonnet tests are least liable to fallacy in this 
respect. 
Nitrites and Formaldehyde.— Mixtures of these 
substances are now sold under fanciful and mis- 
leading names, for milk preservatives as a 
nitrite prevents the reactions of formaldehyde 
with some of the tests. 
Leffmann has found that the phenylhydrazin 
test will react promptly with formaldehyde in 
presence of notable amount of nitrite and also 
