THE TOBACCO BEETLE. 47 



ing from 140° to 194° F. The treatment was said to be thoroughly 

 effective in killing all stages of the beetle, and cigars made from 

 the steamed tobacco were pronounced indistinguishable from those 

 made from unsteamed tobacco, the only apparent damage in any 

 instance being that steaming the wrapper tobacco made it darker 

 and somewhat more brittle. 



EFFECT OF STEAM ON DIFFERENT STAGES OF THE BEETLE LABORATORY EXPERIMENTS. 



At Richmond, Va. (January, 1915), tests were made to ascertain 

 the effect of steaming various classes of tobacco infested with the 

 beetle. Steam under pressure was admitted directly into a tightly 

 closed fumigating drum. Temperature records were obtained by in- 

 serting a chemical thermometer through a cork in the lid of the 

 drum. The eggs used were on bits of leaf tobacco. Examinations 

 of the treated eggs were made after the controls had hatched. All 

 tobacco containing other stages of the beetle was put in seperate jars 

 and sealed after treatment. Each lot was kept under observation 

 for several months. The results of the experiments may be briefly 

 summarized. Thirty-minute exposures at 115 °F. gave practically 

 negative results. All stages of the beetle were killed by the follow- 

 ing exposures: 20 minutes at 160° and 165°F. ; 30 minutes at 163°F. ; 

 1 hour at 138° and 150°F.; 40 minutes at 140°F. 



ULTRA-VIOLET RAYS. 



At the request of a firm manufacturing apparatus for ultra-violet 

 sterilization of water, a series of experiments were made to ascertain 

 the effect of ultra-violet rays on different stages of the tobacco beetle 

 and to determine whether or not the process could be successfully 

 used in sterilizing tobacco. Apparatus for the work was installed 

 at the laboratory at Clarksville, Tenn., the equipment consisting 

 of a mercury arc rectifier for transformation of 110- volt, 60-cycle 

 alternating current to 110-volt direct current, and 2 quartz mercury 

 arc burners operated on direct current at 110 volts and consuming 3.5 

 amperes. The quartz mercury vapor burners, or lamps, were of differ- 

 ent types: One was operated at a voltage of 66-67, consuming 3.3 

 amperes of current, and the other at a voltage of 70-75, consuming 3 

 amperes of current. 1 To avoid any effect of heat, all exposures were 

 made with the material in a quartz glass container under distilled 

 water kept at normal room temperatures (quartz glass and chemically 

 pure water are transparent to the ultra-violet rays) . In experiments 

 with eggs of the tobacco beetle 3 lots were used in each test, arranged 

 as follows : (a) Eggs on upper side of leaf tobacco, (b) eggs on under- 



1 The burners were operated under a hood to protect the eyes of the operator from 

 injury, and glasses were Worn as an additional precaution. 



