BULLETIN 39, UNITED STATES NATIONAL MUSEUM. 



[64] 



ii y 



wide moutli ; break up a quantity of cyanide of potassium into pieces 

 of convenient size (about a cubic centimeter); put these pieces in tlie 

 bottle so that they form an even layer at the bottom ; mix in a con- 

 venient vessel a quantity of plaster of Paris with water just suflicient 

 to make the mixture semifluid and then pour it over the cyanide so as 

 to cover this last to a depth of about 5 millimeters. The bottle is then 

 left open for an hour or two until the plaster is thor- 

 roughly dry. The walls of the bottle are tlien 

 cleansed from particles of the plaster which may 

 have splashed on them, and the bottle is ready for 

 use. If not used too frequently, especially in warm 

 weather, it will last for an entire year or longer. Bot- 

 tles or vials of different sizes can be prepared in the 

 same way, and a very small cyanide vial which can 

 be carried in the vest pocket will be found most 

 convenient for use on all occasions. Fig. 92 repre- 

 sents a medium-sized chemist's test tube, converted 

 into a very convenient cyanide bottle, in which, 

 however, a cotton wad has been used to keei? the poi- 

 son in place. When the collected specimens have 

 been removed from the bottle the latter should be 

 carefully wijDcd clean with a piece of cloth or paper. 

 The surface of the plaster soon becomes dirty and, 

 on account of the hygroscopic property of the cyan- 

 ide, more or less moist, especially during warm 

 weather. The cyanide bottle is, therefore, not well 

 adapted for the killing and temporary preservation 

 of small and delicate specimens. This difficulty can 

 be altogether obviated by placing a circular piece of 

 blotting paper, cut to neatly iit the interior of the 

 bottle, on the surface of the plaster. This can be 

 renewed once a week or so, or oftener if it becomes 

 necessary. It will frequently be advisable, also, 

 especially in the collection of Diptera, Hymenoptera, and other deli- 

 cate insects, to put a strip of blotting paper partially round the inner 

 «ide of the bottle. This will absorb any moisture which may gather 

 on the inside of the bottle and which would otherwise wet and injure 

 the specimens. The accompanying figure (Fig. 93) illustrates a bottle 

 arranged as described above. A similar result is attained by some col- 

 lectors by partially filling the bottle with narrow strips of bibulous 

 paper to support and separate the insects as shown at Fig. 91. 



For delicate specimens, also, the collecting bottle may consist of a test- 

 tube of about the size of Fig. 92. This is half filled with loose, thin 

 strips of soft white paper. A piece of cyanide about the size of a pea 

 is then wrapped carefully in paper and so placed in the middle of the 

 strips that it can not come in contact with the sides of the glass. 



•'«i 



Pig. 92.— Pocket cyanide 

 bottle. 



