22 The Philippine Journal of Science 191s 



potassium cyanide with which these experiments were made was 

 analyzed and found to be 98 per cent pure. 



On November 24, 550 larvae of Lasioderma serricorne were 

 fumigated in tobacco waste for twenty-four hours with the 

 gas liberated from 9 grams of potassium cyanide per cubic 

 meter of compartment, and 171 were killed while 379 lived and 

 developed into adults. 



TEMPERATURES 



Where it is not desirable to use chemical treatment for the 

 control of the cigarette beetle, or in cases where machinery 

 already is installed for steaming tobacco, the manufacturer can 

 resort to steam as a weapon against this pest. The method of 

 storing after treatment described under "Preparation of Factory" 

 would always guarantee the stock. 



In spite of the prejudice against steaming tobacco, experiments 

 in smoking cigars made of steamed tobacco show that the treated 

 cigars, although smoked by habitual smokers, are indistinguish- 

 able from the untreated. The only apparent damage done to 

 the steamed tobacco is that suffered by the finest wrapper. As 

 before stated, steaming the wrapper has a tendency to give it 

 a darker color and the leaf becomes somewhat brittle. However, 

 this can be avoided where the proper drum (Plate IV, fig. 1) 

 is used and wrapper tobacco is placed in the center of the drum 

 with filler tobacco all around it. Experiments have shown that 

 in the treatment of the finest wrapper leaf about 5 per cent 

 of the wrapper that would make claro or Colorado claro cigars 

 must be put into the Colorado, Colorado maduro, and maduro 

 grades. While this causes absolutely no loss of tobacco, the 

 manufacturers deem it a loss because of the preference in the 

 market for the milder or lighter grades of cigars. 



I had the opportunity of using a steaming drum especially 

 prepared for tobacco with a view to the control of the cigarette 

 beetle during the period of this investigation (Plate IV, fig. 1). 

 This apparatus consists of a cylindrical drum within which is 

 a track upon which runs a perforated car large enough to hold 

 about 120 kilograms of leaf tobacco. After the leaf tobacco 

 is placed in the car, it is pushed into the drum, and the door 

 is clamped down tight upon rubber gaskets. The steam can 

 be introduced at any pressure up to 8 atmospheres. The tem- 

 perature in the drum varies from 96° to 102°, depending upon 

 the pressure of the steam from the boiler. Another steam drum 

 (Plate IV, fig. 2), which can be used but which is not as con- 

 venient as the one just described, can be obtained from London 



