302 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



in the bottom of drums and in machines for applying the gas was often 

 noted in field work during this past season, and was a source of inter- 

 ference with accurate action of the pump. 



Actual proof of the fact that where liquids of widely varying purity 

 are brought together stratification may take place and the relation 

 thereto of zinc compounds present features of importance in field 

 practice. In the first place only liquids of uniformly high purity 

 should be used thereby to prevent stratification which might occur 

 if materials of widely different strengths from two or more containers 

 are poured together. Metals containing zinc should not be brought in 

 contact with liquid hydrocyanic acid . When drums are washed out with 

 water after use in the field they should be thoroughly dried before 

 being refilled. Furthermore, that stratification may hasten decompo- 

 sition is shown by one experiment in which a gallon bottle half full of 

 tap water was filled with 92 per cent hydrocyanic acid from a galvanized 

 iron drum. A few days following the experiment decomposition 

 started immediately below the middle layer which held the precipitate 

 and within two weeks the lower half of the bottle was dark brown in 

 color. The top layer remained perfectly clear until the completion 

 of the experiment when the bottle was discarded to avoid explosion. 



Chairman H. J. Quayle: These three papers are now open for 

 discussion. 



Prof. Geo. P. Gray: Our conclusions are the same regarding 

 liquid HON and its abihty to stratify. 



R. S. Woglum: There are a few rather interesting points which 

 I wish to call your attention to in connection with our studies of 

 liquid HON. 



Where the liquid is taken from iron drums the gelatine percipitate 

 is hard to mix with the liquid HON and stratification may be present 

 when it is used. 



There has been more daylight fumigation during the past summer 

 with liquid HON than ever before under the old system of fumiga- 

 tion. However I do not believe in daylight fumigation because the 

 chances for burning are too great. In hot weather the gas from liquid 

 HON stays near the bottom of the tents and gives relatively better 

 killings in the lower portions of the trees. At 40° F. the killing is 

 rather poor, although it lasiy be said that in lower temperatures 

 the best killings are at the top of the trees. 



Chairman H. J. Quayle: Our experiences show that there is 

 less dijffusion in low temperatures. At a temperature of 50° F. there 



