10 
CAUTION. 
It should be remembered that hydrocyanic acid gas is one of the 
deadliest poisons known, fatal to human beings and plants, as well 
as to insects. 
Greenhouses which are within 50 to 75 feet of dwellings should not 
be fumigated unless the windows and doors of the latter on the side 
next to the greenhouse can be closed during the operation. 
The bag containing the cyanide should not be permitted to drop 
into the jar until the operator has left the house. 
It is essential that the exact proportion of cyanide be used at the 
rate designated for each cubic foot of space and that the exposure 
should not exceed the limit ascertained by experiments as appropriate 
to the plants to be fumigated. A greater strength of gas or a longer 
exposure than specified is apt to result in injury to the plants. 
It is best to use this method at first experimentally on a small scale 
before attempting the fumigation of an entire greenhouse, and a pre- 
liminary test should always be made in case plants of a species or 
variety not previously fumigated are to be treated. ; 
ALBERT FEF. Woops and P. H. DORSETT. 
Approved : 
JAMES WILSON, 
Secretary. 
WASHINGTON, D. C., January 10, 1899. 
e) 
