164 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
states varies considerably for the same kind of nursery stock. The 
following formula to the one hundred cubic feet is used by many of 
the states for dormant stock: 
1 Ounce of Sodium Cyanide 
2 Fluid Ounces of Sulphuric Acid 
4 Fluid Ounces of Water 
The amounts of acid and water considered necessary to generate 
the gas with one ounce of sodium cyanide varies in several states. Only 
one fluid ounce of sulphuric acid is used in some of the states, one and 
a half ounces in others, and three ounces in a few states in connection 
with the one ounce of sodium cyanide. The amount of water used 
with an ounce of the cyanide is only two fluid ounces in some states and 
three in others. 
It is recommended in most of the states that exposure to the gas 
be from forty minutes to one hour. Many states consider a thirty 
minute exposure as ample, while on the other extreme one of the states 
in the Northwest specifies an exposure to the gas of ninety minutes. 
Many of the State Inspection Officials have apparently overlooked 
the fact that sodium cyanide give one-fourth more gas than potassium 
cyanide. The fumigation dosages worked out years ago on the basis of 
potassium cyanide do not seem to have been lowered any by its re¬ 
placement within recent years by sodium cyanide. 
In my opinion, it would not be feasible for all the states in the country 
to attempt the adoption of a standard fumigation schedule for nursery 
stock. This is due chiefly to the great differences in humidity and tem¬ 
perature in the different states at the time the plants are fumigated. 
Experiments conducted by the Federal Horticultural Board at one of 
the Cotton Fumigation Plants in Boston demonstrate clearly that it 
is difficult to kill insects by fumigation when the weather is extremely 
cold. In these experiments Brown-tail moth larvae and European 
Corn Borers were subjected to a dosage of six ounces of sodium cyanide 
to the one hundred cubic feet in a vacuum for two hours with the result 
that at extremely low temperatures some of the larvae were still living 
at the conclusion of the experiments. Please note that this dosage is 
several times that ordinarily used for nursery stock, and it would appear 
doubtful whether nursery stock could survive so much hydrocyanic 
acid gas. 
It would seem that the states in a group where the temperature and 
humidity conditions were very nearly uniform could adopt uniform 
fumigation regulations. For example, all Southern States shouldrecom- 
