11 



25. Tobacco. 



Various firms sell paper rolls soaked in tobacco extract to 

 burn in houses. Tobacco extracts of various strength can also 

 be obtained, to evaporate over stoves. The stronger extracts 

 are usually quite effective against plant lice if the house is tight. 



26. Carbon Disulfid. 



Use 2 pounds of carbon disulfid to every 1,000 feet of space, 

 pouring it into shallow dishes in the upper part of the place to 

 be fumigated. Close everything tightly and leave for twenty- 

 four hours. Open and air for ten minutes before entering or 

 using anything fumigated. Do not use this treatment in any 

 place near a fire, hot steam pipes or where there is much heat, 

 as the disulfid catches fire easily, even from a lighted cigar. 



27. Hydrocyanic Acid (for Nursery Stock). 



Potassic cyanid (98 or 99 per cent.). 



SuKuric acid (1.83 specific gravity commercial). 



Water. 



Multiply the number of cubic feet to be fumigated by .2 or 

 .25, giving the number of grams of cyanid needed for the 

 house or box; divide this by 28.35, giving the weight of the 

 cyanid in ounces. Take 1 fluid ounce of acid and three times as 

 many fluid ounces of water as was taken in ounces by weight 

 of the cyanid. Mix the water and acid in an earthen or granite 

 ware jar, then by loose bag and string drop in the cyanid 

 after tightly closing the place to be fumigated. Leave closed 

 forty minutes, then open from the outside and air for at least 

 ten minutes before entering. 



28. Hydrocyanic Acid (for Empty Houses). 



Potassic cyanid (98 or 99 per cent.), 1 ounce per 100 cubic feet. 

 Sulfuric acid (1.83 specific gravity commercial), 1 fluid ounce 



per 100 cubic feet. 

 Water, 3 fluid ounces per 100 cubic feet. 



Mix and use as directed under No. 27. 



