JOim OF AGRIdTURAL RESEARCH 



DEPARTMENT OF AGRICULTURE 



Vol. VI Washington, D. C, June 12, 1916 No. 11 



EFFECT OF RONTGEN RAYS ON THE TOBACCO, OR 

 CIGARETTE, BEETLE AND THE RESULTS OF EX- 

 PERIMENTS WITH A NEW FORM OF RONTGEN TUBE 



By G. A. Runner, 



Entomological Assistant, Southern Field Crop Insect Investigations, 



Bureau of Entomology 



INTRODUCTION 



The Rontgen tube used in experiments on the efifect of Rontgen rays 

 on the tobacco, or cigarette, beetle (Lasioderma serricorne Fabricius) 

 described in this paper is a new form designed by Coolidge.^ By this type 

 of tube a much more powerful Rontgen-ray radiation can be maintained 

 than was possible with the apparatus used in experiments of a similar na- 

 ture previously made by the writer. The intensity and the penetrating 

 power of the Rontgen rays produced are both under the complete control 

 of the operator, and many of the factors limiting the use of other types 

 of tubes for the special purpose desired are absent. The tube can be 

 operated continuously for long periods without showing an appreciable 

 change in either the intensity or the penetrating power of its resulting 

 radiation. The starting and running voltage are the same. The resulting 

 radiation is therefore homogeneous and of any desired penetrating power. 



The ordinary forms of tubes used in previous experiments were incapa- 

 ble of being operated continuously without change in penetrating power. 

 Owing to the fluctuation in intensity and penetrating power incidental 

 to frequent adjustment, it was impossible to tell with any degree of 

 accuracy the dosage and amount of radiation. 



In previous experimental work with Rontgen rays it had been found 

 that in sterilizing cigars or tobacco, small dosages are ineffective, from 

 a practical standpoint. To be effective, the radiation must be intense, 

 and it is evident that if the process can be successfully applied to com- 

 mercial work, the apparatus used must be capable of producing and 

 ma'ntaining such radiation during the entire period required for the 

 material treated to pass through the exposure chamber of the machine. 



' Coolidge, W. D. A powerful Rontgen ray tube with a pure electron discharge. In Phys. Rev., s. 2. 

 V. 2, no. 6, p. 409-430, 6 fig. 1913. 



Journal of Agricultural Research, Vol. VI, No. 11 



Dcpt. of Agriculture, Washington, D. C. June 12, 1916 



^" /ON ^-J5 



(383) 



