A piece of heavy blotting paper or heavy cloth soaked with chloroform or ether or benzine and placed at the bottom of a jar or bottle makes an excellent killing bottle for large-sized insects. For smaller specimens the collecting vial should be half filled loosely with narrow strips of soft paper, upon which a few drops of the liquid are poured, not so much, however, as to wet the paper. While collecting, the vial must be kept closed as much as possible. Some collectors prefer chloroform, others ether. If this method of killing is practiced with the necessary care, there is no objection whatever to it; the specimens are not wetted as they are in alcohol, and remain cleaner than those killed by any other method. The drawback is that the substances mentioned evaporate very rapidly and have to be renewed even on short excursions. On account of this great volatility, one can never be certain that all the specimens in the collecting bottle are dead after a given time and there is always some danger that one or the other of the hardier insects may regain activity. What mischief such revived specimens are capable of doing, many collectors have experienced to their sorrow. Another disadvantage of these volatile substances is that if used in too large quantities they will, in delicate specimens, especially beetles, cause an extension of the soft ligaments between the head and prothorax or between the latter and the mesothorax, and thus bring the specimen into an unnatural position, or cause the head, or head and thorax to drop off. _Cyanide of Potassium._--The method of killing which, of late years, has found most favor with collectors, is the use of cyanide of potassium. For killing large sized specimens they are simply put in what is now universally known as the "cyanide bottle." This may be constructed as follows: