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 José 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). 
