THE MONTHLY BULLETIN. 



287 



KILLING. 



Insects to be mounted and preserved should be killed as soon after 

 collected as possible. The most popular method of killing is the use of 

 a jar or can containing potassium or sodium cyanide. The cyanide 

 may be kept in the bottom of the jar or can with plaster paris, or better, 

 with suitable pieces of blotting paper, which absorb the moisture. The 

 lid should be tight, so as to retain all of the fumes, and enough cyanide 

 used to make the killing rapid. Small killing-vials, suitable for the 

 pocket (Fig. 287), are very desirable and easily made. Baking powder 



Fig 289. — Glass covered exhibition case for pinned insects. 



cans are also excellent containers, as they cannot be broken, but due to 

 the poor fitting of the lids need often to be refilled. In preparing such 

 a can, cut a circular piece of blotter to cover the bottom ; add the cyanide 

 and pack cotton or other material tightly around it; cover all with 

 several circular, tight-fitting pieces of blotter, and then cut another 

 piece large enough to form a lining inside the can, reaching from the 

 pieces holding the cyanide to the top. When the lid is on. this lining 

 will hold the cyanide in the bottom of the can and is also an excellent 

 absorbing surface for any excess moisture. All cyanide killing recep- 

 tacles should be plainly marked poisonous. 



