THE CONTROL OF HUMAN LICE 325 



34 (1910) with special reference to ships, and in Entomology Bull. 60 

 (1906) with reference to general fumigation. 



1. Clayton gas is generated by burning common roll brimstone 

 in an oven or generator outside of the building. A very high heat is 

 generated. The gas is passed over two baffle plates before reaching 

 the outlet pipe which is cooled by water circulating in pipes around 

 it in an ordinary'steam boiler tank. The gas then is passed into the 

 building to be fumigated. This gas is a mixture of sulphur dioxide 

 and sulphur trioxide. As the gas is heavier than air there must be 

 circulation through the roof of a building or hatch of a ship until the 

 gas begins to come out in quantity. 



2. Bum sulphur candles, being careful to isolate them by sufficient 

 metal from all woodwork, at rate of 4< pounds per 1,000 cubic feet 

 for ,6 hours. 



b. Cyanide is one of the best known gases used for fumigation. 



1. Sodium cyanide only is now available. Generate in earthen 

 jars, placing in the jar 1% oz. sulphuric acid and 2 oz. water to every 

 ounce of cyanide to be used. Arrange the cyanide in a package sus- 

 pended over the jar so that it can be released by the operator at a 

 distance by pulling or releasing a cord. The gas is generated very 

 rapidly and is exceedingly dangerous. Use 10 oz. of cyanide for each 

 1,000 cubic feet and expose for 2 hours. This will kill all other insects 

 present. 



2. Potassium cyanide should be used at the rate of 1 oz. cyanide 

 to 1 oz. sulphuric acid, and 3 oz. of water. 



3. Chlorocyanogen (CICN), in experimental work, gives promise 

 of being fully as effective as HCN and much safer to use, because the 

 irritation of the membranes of the nose and eyes gives warning of any 

 leak long before sufficient gas has escaped to produce any toxic effect. 

 The most practical method for fumigation of any kind would be a 



mobile motor furtiigator with hose attachments^ capable of treating any 

 building, tent, or car. If this unit had a tight fumigation room, gar- 

 ments could be hung therein and practically fumigated. The installa- 

 tion should be equipped with generators for cyanide, formaldehyde, or 

 sulphur fumigation, and be placed in charge of practical fumigation 

 experts. 



Vacuum fumigation has received several very successful trials. On the 

 Mexican border it has been used by the Public Health Service, where 

 a hydrocyanic acid gas fumigation is used. Many steam sterilizers now 

 in use are available for gas fumigation. The following formulae have 

 been tested and proven satisfactory: 



1. For chests, trunks, and tightly-packed garments 25-inch vacuum. 



