FIELD WORK ON INSECTS. 53 



along with you to the collecting field should go several 

 small boxes rather than one big box. Remember, your 

 first object is to bring home your insects alive to find out 

 about them, and whether to kill them or not. A cyanid 

 bottle may also be used for one of the killing bottles ; but 

 extreme care must be observed in the use of it, as the cya- 

 nid is a deadly poison, and the bottle must be kept always 

 corked; it would much better always be left at school, 

 and the safer chloroform or ether bottle taken to the field. 

 When one has become something of an expert in hunting 

 and trapping insects the cyanid bottle becomes a safer 

 companion on the various expeditions. 



If the instructor decides that it may be used, it may 

 be made in this way. A wide-mouthed bottle should be 

 chosen, and into it may be dropped some small lumps of 

 potassium cyanid. As long as this substance is kept dry 

 it does little harm and may be safely handled with the 

 hands dry. Then on this is to be dropped a small quantity 

 of powdered plaster of Paris, also dry, enough to fill the 

 spaces lightly between the cyanid lumps. Then mix up a 

 small quantity of plaster of Paris in water, enough to cover 

 the dust and lump mixture about an eighth of an inch 

 deep, using enough water to have it spread easily. Run 

 .this in on to the mixture, doing it as quickly as possible 

 and taking care to leave a small opening _ somewhere 

 through which you may at the very last pour in a wee bit 

 of weak sulphuric acid on to the cyanid lumps which may 

 be there, afterward quickly covering this opening v\'ith 

 the wet plaster also. Take care to do all this in an open 

 room with the windows open; then there will be no danger. 

 This makes the most effective killing bottle for the gen- 

 erality of insects; and if used rightly, with due caution, 

 and always kept tightly corked it will be found satisfactory. 



