492 STATE BOARD OF AGRICULTURE. 



l)on hisnlpliifl in f\iinipntion naainst insects.* The anthors found flint 

 "if the material were a cheap product, it might prove a substitute for 

 carbon bisulphid if used in strength gi-eater than ten pounds to one 

 thousand cubic feet." 



Later still (Mav, 1913), Professor H. Garmau of the Kentucky station 

 stated that, as the largest amount of carbon tetrachloride used in a series 

 of tests, 20.8 ozs. to 100 cubic feet killed 100 per cent of the insects in 

 nine cases out of twelve. f 



In the Spring of 1914, a request came from the J. W. Knapp Depart- 

 ment Store of Lansing, Michigan, asking for some safe means of insur- 

 ing valuable furs, stored in a small room, against moths during the sum- 

 mer. The ''fur room" was 4x014x0^2 feet — the side walls tightly built 

 of matched lumber, the ceiling of glass. It was located in the large 

 cloak and coat department room, where it was very accessible; but any 

 fumigant used had to be as inoffensive as possible, without especial dan- 

 ger to human life, and without the entailment of extra fire risk. Carbon 

 tetrachloride suggested itself as the possible, satisfactory fumigant in 

 this case. Further laboratory tests had shown the writer that with or- 

 dinary wooden enclosures, whicli were not practically gas-tight (as was 

 the case Avith the glass flasks), perfect fumigation could not be obtained 

 at usual room temperatures (G8° to 70° F), even when the carbon 

 tetrachloride was exposed in a wide vessel. The vapor slowly escaped 

 from the walls of such enclosures, and evaporation did not go on rapidly 

 enough at even 70° F. to bring about the necessary concentration for 

 perfect fumigation. It Avas necessary to use heat and vaporize the liquid 

 quickly. Dr. Britton had experienced a someAvhat similar difficulty in 

 volatilizing this liquid in his experiments Avith nursery stock. He final- 

 ly resorted to the use of heated cast iron pans for generating the vapor 

 more quickly (citation given above). Recommendation Avas made in this 

 instance, therefore, that six pounds of carbon tetrachloride be vaporized 

 from Avide, heated pans placed near the ceiling of the "fur room" — 

 and that the charge be started immediately after closing hours in the 

 evening. According to this recommendation, the liquid carbon tetra- 

 chloride Avas used at the rate of about 3.55 pounds to 100 cubic feet of 

 room space. Heat for vaporization was supplied by hot, flat soapstones 

 laid on iron brackets. The wide pans of carbon tetrachloride were set 

 on the hot soapstones and the room AA'as quickly closed. In the case of 

 the first charge tried, the stones had not been made hot enough and not 

 quite all the liquid insecticide had evaporated eA-en after twenty-four 

 hours. Several adult moths {Tinea Uselliella) had been placed in a 

 wire cage in the room. These Avere quiet Avhen the cage was remoA^ed at 

 the end of the tAventy-four hours period, but after about four hours in 

 fresh air tAvo moths recovered enough to be able to move their legs. Hoav- 

 ever, none ever recovered entirely. Another charge Avas made Avith six 

 pounds of the carbon lelrachloi-ide, and this time the soapstones Avere 

 made very hot so that the liquid vaporized rapidly. A cage of moths 

 could be observed through the glass roof of the room. They quickly be- 

 came quiet. Before morning all the liquid insecticide had been vaporiz- 

 ed. The cage was removed after thirty-six hours, and the moths were 



•BuUetin No. 96, Part IV, 1911 ; Bureau of Entomologj-, TT. S. Dcpt. of Agriculture. 

 1 Kentucky Sta. BiiHrfiu No. 172, p. 200. 



