Vol. L1X. No. 2606. 
NEW YOKE, JANUARY 6, 1900. 
$1_PER YEAR. 
THE USE OF HYDROCYANIC ACID GAS. 
FOR KILLING INSECT PESTS AND VERMIN. 
Its Use Outdoors and in Buildings. 
Part I. 
IN THE NURSERY.—Maryland was the first State 
to require by law the fumigation of nursery stock for 
the suppression and control of certain injurious in¬ 
sects. This section of our law was suggested and in¬ 
serted by our nurserymen themselves, as they fully 
realized the great risks they were taking by exchange 
and purchase of buds, grafts and scions from various 
places. The wisdom of the step has been proven by 
the good results and increased sales of nursery stock 
made in this State during the past two years. We 
have now in operation 37 houses for fumigating pur¬ 
poses, through which from 5,000,000 to 6,000,000 fruit 
trees are passed annually. 
The Canadian government has adopted our system 
of fumigation, and now has 70 houses in operation in 
the Province of Ontario, under the supervision of 
Prof. William Lockhead, of the Agricultural College 
at Guelph. Hundreds of nurserymen in other States 
are making inquiry about our system, management 
and construction of houses. The whole process is so 
simple and easy, that there ^s no excuse for a nur¬ 
seryman taking so many chances of getting or send¬ 
ing out nursery stock that is not all right. In fact, 
it is the only practical safeguard he has; and, so far 
as the planter is concerned, it affords him the great¬ 
est possible protection under existing conditions. 
Never in the history of American horticulture, was 
there a time when nurserymen and growers should be 
as careful as now. The eyes of a critical world are 
upon us. Do not be deceived by the cry, “All is 
talk!” “There is nothing to fear,” etc. For my part, 
I nave seen and experienced enough, to 
beseech the nurserymen and fruit grow¬ 
ers to beware! beware! Let eternal vig¬ 
ilance be the order of the day. 
HOUSES OR BOXES used for fumiga¬ 
tion, are varied in size, to accommodate 
the grower, in accordance with the 
amount of stock grown or handled. For 
illustration, we have one house that will 
hold from 12,000 to 15,000 first-class 
trees; and several, whose capacity is 
from 5,000 to 10,000. Others are smaller, 
holding from 1,000 to 4,000 trees, while 
small lots of a few hundred are placed 
in a box. In most of our houses the 
trees are put in by hand. One firm, 
however, handling from 1,000,000 to 
2,000,000 trees annually, has two rooms 
large enough to admit a wagonload of 
trees at one time, as shown in Fig. 2. 
If only a small lot of stock is handled, 
a box from seven to eight feet long, by 
three feet wide and 3 y 2 feet deep, will 
answer the purpose. It should oe made 
of good pine boards, lined inside with 
heavy building paper, with edges over¬ 
lapped, paint between laps, and finally 
lined with tongued and grooved floor¬ 
ing. Unless desirable, there is no neces¬ 
sity for a lid. The trees can be packed 
in the box, and held in place by means 
of a couple of cleats; then turn box face downwards 
on a smooth surface, tramp a little dirt around the 
edges, and all is ready for the chemicals by tilting the 
box slightly so as to admit the vessel containing acid 
and water. 
POINTS TO REMEMBER.—One thing must be 
borne in mind all the time, and that is, the receptacle 
must be gastight. The building will, therefore, admit 
of no slovenly workmanship. One of our large houses 
is divided into two large rooms, 15x14x7 feet; and two 
smaller rooms on the end 4x5x7; the entire building 
being 32x16 feet, with a roof pitch of two feet. As a 
rule, it is desirable in most cases, where several thou¬ 
sand trees are handled, to have a house built with one 
large room and two small rooms; one of the latter 
being used for a chemical and storeroom, and, there¬ 
fore, not lined. The other small room should be fit¬ 
ted up for fumigating small lots of trees, thus saving 
A MARYLAND FUMIGATING HOUSE. Fig. 1. 
expense that would be required for the large room. 
A house of this kind is shown in Fig. 1. 
Instead of constructing a separate building for 
fumigating, very often a nurseryman has a packing 
shed, in one end of which he can build his room. 
He can cover the frame inside with boards; then put 
on three-ply cyclone or rawhide building paper, and 
finally the flooring. In every case, have a good 
smooth surface on which to secure the paper. The 
flooring is then joined very easily, and will be tight. 
M 
The ceiling and floor should be lined and constructed 
in the same manner. In some cases, where a good 
solid clay floor can be had, it will answer the pur¬ 
pose, care being taken to see that the house is abso¬ 
lutely tight at the ground surface. As a rule, a ceil¬ 
ing seven to eight feet high is the most convenient 
and economical. If it is higher there is usually much 
space lost at the top of the room, adding to cost of 
Chemicals. 
In constructing a house or room of any kind, great 
care should be taken to have a flue or small door for 
ventilating purposes on the side where there would be 
least danger of the gas being inhaled. In some in¬ 
stances the ventilator leads out of the top of the 
building. This, of course, is the safest plan; but the 
small door is most commonly used. The main door 
to the house should be, at least, 3% feet wide by six 
or 6 y 2 feet high, made heavy, and refrigerating style. 
It should be hung by means of three heavy strap-iron 
hinges, and kept closed by bolts at the top and bot¬ 
tom, and possibly a lock in the middle. The trees 
are piled loosely, not packed, on the floor, with roots 
toward the walls, tops overlapping, and when the de¬ 
sired number have been placed, the chemicals are 
added. 
MAKING THE GAS.—The chemicals needed are: 1, 
potassium cyanide, guaranteed 98-99 per cent pure; 
2, the best grade commercial sulphuric acid (specific 
gravity 1.83), and 3, water. The cyanide should be in 
lumps about the size of shell-bark hickorynuts. It 
costs from 30 to 35 cents per pound in 25 to 100-pound 
cans. The acid costs about two cents per pound by 
the carboy. The amounts necessary for a room are 
estimated in terms of cyanide per cubic foot of space 
enclosed. For example, the large room shown in Fig. 
2 contains 564 cubic feet. We use .25 (twenty-five- 
hundredths) gramme of cyanide for each cubic foot. 
We therefore multiply 564 by .25. Thus, 564x.25= 
141.00 grammes of cyanide. To reduce this to ounces 
we divide 141.00 by 28.35, as there are 28.35 grammes 
in an ounce. Thus, 141.00-^28.35=five ounces (a frac¬ 
tion less), the amount of cyanide needed for the 
house. The other chemicals are easily determined, 
as a half more acid, liquid measure, than cyanide, 
and a half more water than acid. Thus the room 
needs five ounces cyanide (by weight), 
7% ounces acid (liquid measure), and 
1VA ounces (liquid measure) of water. 
WHAT TO DO.—In combining the 
chemicals, 1, measure the acid in a glass 
beaker (marked ounces), and pour it in 
a small two to four-quart earthenware 
crock or pickle jar; 2, measure water 
and pour this on the acid; 3, then drop 
in bag of cyanide, which has been pre¬ 
viously weighed, close door quickly, and 
leave desired length of time. Usually 30 
to 45 minutes is long enough to expose 
any nursery stock. Use the normal dose 
(.25 gramme) on all dormant, well- 
matured stock. If fumigating June- 
budded peach or peach under three feet 
(whips), the dose should be reduced to 
.18 gramme per cubic foot. For Woolly 
aphis on apple and Black aphis on 
peach the .18 gramme dose is sufficient 
for a half-hour exposure. 
Caution:—1. Be sure that nobody en¬ 
ters the room during fumigation; 2, see 
that the door and ventilator is open at 
least 10 minutes before anybody enters 
the room; 3, after fumigation, empty 
contents of jar and cover with earth; 
4, never use more than .25 gramme per 
cubic foot space inclosed; 5, never fumi¬ 
gate peach the second time; 6, never 
leave cyanide exposed to the air, it must be kept in 
closed vessel; 7, remember at all times that the gas 
must not be inhaled, as it would prove fatal; 8, keep 
the cyanide out of reach of children, and always label 
can poison. 
By a long series of experiments the past Spring, I 
have determined the maximum resisting powers of 
various grades and kinds of nursery stock. These re¬ 
sults will soon be published in bulletin form. The 
A LOAD OF TREES FUMIGATED AT ONE TIME. Fig. 2. 
