The.Capture, Preparation, and Preservation of Specimens 
then applied to these upturned edges; and it is inserted into the 
jar and pasted securely over the cyanide by the upturned flaps. 
A jar thus charged will last for a long time, if kept properly closed 
when not in use. Cyanide of potash has a tendency to deliquesce, 
or melt down in the presence of moisture, and in very humid cli¬ 
mates or damp places, if the jar is not kept well stoppered, the 
cyanide will quickly become semi-fluid, the paper will become 
moist, and specimens placed in the jar will be injured or com- 
pletely ruined. It is well, however, to bear in mind the fact that 
the fumes of hydrocyanic acid (prussic acid), which are active in 
producing the death of the insect, will not be given off in suffi¬ 
cient volume unless there is some small amount of moisture pres- 
Fig. 48.— Method of disabling a butterfly by pinch¬ 
ing it when in the net. 
ent in the jar; and in a very dry climate the writer has found it 
sometimes necessary to add a drop or two of water from time to 
time to the cyanide. The same method which has been described 
for charging a jar with cyanide of potash can be employed in 
charging it with carbonate of ammonia. 
Field-Boxes .—In collecting butterflies it is often possible to 
kill, or half kill, the specimens contained in the net by a smart 
pinch administered to the insect by the thumb and the first finger, 
the pressure being applied from without the net (Fig. 48). This 
mode of procedure, however, unless the operator is careful, is apt 
to somewhat damage the specimens. The writer prefers to hold 
the insect firmly between the thumb and the first finger, and apply 
a drop or two of chloroform from a vial which should be carried in 
30 
