52 
INSTRUCTIONS FOR 
CYANIDE KILLING- 
BOTTLE. 
COLLECTING-TIN. 
the bottom put about 1 ounce of fused cyanide 
of potassium broken into small fiagments, then 
enough dry plaster of Paris nearly to cover it 
(filling in the interspaces), and on to the top of 
this pour some plaster mixed with water to the 
consistency of thick cream, to make about |-inch 
thickness over the cyanide. As some heat is 
generated during this process, it is well to stand 
the bottle in warm water to prevent it cracking. 
Besides this portable bottle it is well to have a 
larger jar, similarly made, for killing specimens 
when taken home.* 
Collecting-tin .—This is very useful for some pur¬ 
poses. It has a false bottom of perforated zinc. 
In the space at the bottom is placed some blotting- 
paper, with a few drops of chloroform or pure 
benzole. The insects are put into the upper part ; 
and to prevent them rolling about, it isw^ell to put 
some crumpled pieces of blotting-paper in first. 
* If it is intended to take cyanide to a damp tropical climate, it should be 
conveyed in the form of lumps, in a bottle with a tightly fitting glass stopper. 
Cyanide of potassium is also sold in rods, and, in this form, might be con¬ 
veniently carried in short lengths in hermetically sealed tubes of glass, of 
diameter and length just sufficient to take the section of cyanide rod. These 
should be properly labelled, and marked “ Poison.” 
Cyanide killing-bottles can be procured ready for use from Hinton & Co., 
Bedford Street, London, W.C., or any other chemist will prepare one to order. 
The exact amount of cyanide of potassium to be used is of no great conse¬ 
quence ; but in the case of a properly prepared jar the odour should be readily 
perceptible on removing the lid : if it is not, the reason may be that the 
mixture is too dry, when a little water poured on to the top layer will pro¬ 
bably set matters right. After some months’ use the cyanide loses its efficacy 
(to obviate this so far as possible the jar should never be allowed to remain 
open), and the mixture must then be renewed. 
A rough-and-ready method of making a killing-jar or bottle is to cover the 
bottom with a layer of powdered cyanide, and to place above this a number of 
layers of blotting-paper. The layers of blotting-paper immediately in contact 
with the cyanide must be slightly damped; but only r sufficient water should be 
used to cause the cyanide to give off its odour. The top layer of blotting- 
paper must on no account be wet, and the less water used the better. 
