272 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908. 



The plants were then set in the garden, grew well, and showed no 

 sign of scale during the season, or of injury froni the treatment. 

 However, with some of the gases it was necessary to guess at 

 the quantities, but we sought to kill the scale, and expected that 

 many of the trees might be injured. I am now convinced that 

 further tests with some of the gases, especially carbon tetra- 

 chloride, in smaller quantities are desirable. 



Baldwin apple and peach of several standard varieties were 

 the trees used. All were more or less infested with San Jose 

 scale, though none so badly as to seriously affect their vitality. 

 Both roots and tops were fumigated, the trees properly labeled 

 and planted in nursery rows on the station grounds, where they 

 could be watched during the season. In all 359 trees were 

 treated. The following table shows the number treated by each 

 kind of gas : 



Apple ' Peach 



Carbon disulphide 59 61 



Carbon tetrachloride 47 60 



Sulphuretted hydrogen ' 10 15 



Chlorine 25 22 



Hydrocyanic acid gas 20 "40 



Total 161 198 



The details of each test, with results, are given in the following 

 descriptions and tables. 



Volatile Liquids. 

 Carbon Disulphide. 



Carbon disulphide (CS2) is a heavy liquid having a specific 

 gravity of 1.29 and a boiling point of 115° F. Thd vapor is 

 inflammable, and ignites in air at about 300° F. It is 2.63 times 

 as heavy as atmospheric air, and one volume of the liquid 

 evaporates to make about 375 volumes of vapor. Pure carbon 

 disulphide is colorless and has no unpleasant odor, but the com- 

 mercial article has a yellowish color and an extremely disagree- 

 able odor, both of which are due to impurities which enhance 

 its poisonous qualities.* The price varies from, fifteen to twenty 

 cents per pound, but it is cheaper in large quantities. 



* Farmers' Bulletin 145, U. S. Dept. of Agr., Washington, D. C, 1902. 



