. Elementary entomology . searched for any nymphs or larvae that may be entangled in it. This form of net is particularly useful in' collecting dragon-fly nymphs, and is much superior to the ordinary garden rake, which has often been recommended for this purpose. Cyanide bottle (Figs. 472 and 473). These bottles should be provided in at least three sizes, the largest with a di- ameter of two and one half inches or more, a smaller, straight- necked bottle with a diameter of an inch and a half, and an- other much smaller straight-necked bot- tle with a diameter of about half an inch. Before much
. Elementary entomology . searched for any nymphs or larvae that may be entangled in it. This form of net is particularly useful in' collecting dragon-fly nymphs, and is much superior to the ordinary garden rake, which has often been recommended for this purpose. Cyanide bottle (Figs. 472 and 473). These bottles should be provided in at least three sizes, the largest with a di- ameter of two and one half inches or more, a smaller, straight- necked bottle with a diameter of an inch and a half, and an- other much smaller straight-necked bot- tle with a diameter of about half an inch. Before much collect- ing is done, the stu- dent will probably find it necessary to provide himself with two complete sets of these bottles, with possibly one or two extra of the smaller sizes. Cyanide bottles are made in the following manner: Place a few good-sized pieces of potassium cya- nide (a most deadly poison) in the bottom of each bottle, and cover the cyanide with dry plaster of Paris. (As the fumes of potassium cyanide are very poisonous, it should be handled with extreme care.) Then mix up a thick paste of plaster of Paris and water, and pour over the dry plaster in the bottles. Leave standing open for a few hours, until the water has evaporated
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Keywords: ., bookcentury1900, bookdecade1, booksubjectentomology, bookyear1912
