52 



INSTRUCTIONS POR 



CYANIDE KILLING- 

 BOTTLE. 



the bottom put about 1 ounce of fused cyanide 

 of potassium bi'oken into small fragments, 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 :j-inch 

 thickness over the cyanide. As some heat is 

 generated during this process, it is well to stand 

 the bottle in waim 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 is well 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 Iwnps, 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 roufih-and-remhj metliod of viaking a Idlling-jar or bottle is to cover the 

 bottom with a layer of powdered cyanide, and to place above this a number of 

 layers of blotti-ng-paper. The layers of blotting-paper immediately in contact 

 with the cyanide must be slightly damped ; but only sufficient water should be 

 used to cause the cyanide to give off its odour. Tlie top layer of blotting- 

 paper must on no account be wet, and the less water used the better. 



COLLECTING -TIN. 



