3 
damage to carpet or rugs by the possible spattering of the acid acting 
upon the cyanide. All windows must be closed, and if they are not 
tight they should be calked with thin paper or cotton batting. Then 
the operator, beginning at the top of the house, drops the proportionate 
amount of cyanide of potassium, previously weighed out into thin paper 
sacks, into each washbowl, running rapidly from room to room and 
instantly closing the door behind him, descending ultimately to the 
ground floor or even to the cellar, running finally into the open air 
through the open door, which is instantly closed. 
Hydrocyanic-acid gas is lighter than air and consequently rises. 
Therefore, the operation must be begun at the top of the house. The 
next morning the operator returns to the house, opens the last door, 
allows a certain amount of airing; then enters hurriedly and opens the 
windows of the first room or floor; then, after the thorough airing of 
this one, another in turn, thus gradually airing the whole house. The 
fumes quickly overcome and are fatal to human beings; hence the 
necessity for the utmost care and greatest speed in the initial operation 
and in the subsequent airing, and the undesirability of performing the 
experiment alone. The house should not be reinhabited until all trace 
of the odor of the gas has disappeared. This odor resembles that of 
peach kernels. 
The experience of Mr. Marlatt and Mr. Kirkland indicates that the 
operation can be safely performed in the manner indicated, but there 
is another way which was originally invented in greenhouse work. 
An ingenious person, by means of strings and improvised pulleys, can 
arrange it so that standing outside and ioosening the string the 
cyanide suspended over the receptacle may be dropped simultaneously 
into the sulphuric acid. It will be, perhaps, not necessary to go into 
details, since any ingenious person can devise such an arrangement. 
It is, however, not so certain as dropping the cyanide by hand, since 
a caught string here or there might lessen the completeness of the 
fumigation. 
While the writer must again emphasize the dangerous and even fatal 
qualities of this gas when breathed by human beings, it is worthy of 
remark that in the thousands of operations which have been carried 
on with this gas in specially constructed houses for the fumigation of 
nursery stock in the different parts of the country, no cases of fatal 
accident to a human being have ever been recorded. In one instance 
mentioned by Prof. W. G. Johnson, a careless negro was overcome by 
the gas and was removed from the inclosure (dragged out by the feet) 
before serious results followed. 
It follows, from what we have just said, that there may be danger 
from fumigating one house in a row of houses separated only by 
party walls, the other houses being inhabited. Unnoticed cracks in 
a wall would admit the poisonous gas to the neighboring houses. In 
