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 wiien 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 butterllies 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 



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