230 NEW YORK STATE MUSEUM 



specially liable to occur when large amounts are used. Great care 

 should be exercised in handling the cyanide, the acid, and in opening 

 after fumigation. The substances used are deadly. Even a slight burn 

 from sulfuric acid is very painful. 



Recent experiments by Prof. Johnson show that in Maryland growing 

 trees can be treated with this gas and every scale insect killed. The 

 results obtained in some other eastern states are not so favorable, and, as 

 an outfit for trees of any size is quite expensive, it is hardly probable 

 that it will come into general use, unless it is undertaken by experienced 

 persons who would go from place to place and fumigate wherever 

 desired. It can be used to very good advantage in freeing greenhouses 

 from animal pests of all kinds, and when it becomes better known may 

 be more generally employed. In treating the various plants in green- 

 houses, the amount of gas necessary would not be so great as in the case 

 of the San Jose scale. The formula given above would produce enough 

 gas for at least every 150 cubic feet of space, and the action should not be 

 continued over 30 minutes. Dr Jabez Fisher, of Fitchburg, Mass., 

 recommends the use of this amount in greenhouses for from 1,000 to 

 2,000 cubic feet of space, allowing the gas to act all night {American 

 gardening. 1898. 19:741). 



