FLORIDA STATE HORTICULTURAL SOCIETY. 
63 
nia at present to use untreated tents— 
that is, tents which have not been 
treated with any material either by 
dipping or painting for the purpose of 
making the canvas more nearly gas 
tight. This is not the result of such 
treatments having proven unnecessa¬ 
ry, but seems rather to be due to the 
practice of fumigating by the contrac¬ 
tor system, whereby the contractor for 
a certain price per tree furnishes the 
equipment and labor and the owner of the 
grove supplies the chemicals. The contrac¬ 
tor naturally prefers to use a larger 
amount of the chemicals per tree rather 
than to be put tO' the expense of treating 
his tents so as tO' better confine the gas. 
A tanning solution obtained from tan¬ 
neries and known as ‘^oak ooze”, and 
a decoction made from the prickly pear 
cactus, have been used extensively in 
California in years past for increasing 
the tightness of the tents. Linseed oil 
and flexible paints have also been used, 
to some extent. The subject O'f the de- 
sirablity of treating tents is one which 
needs further investigation. 
Tents when not over 48 feet in di¬ 
ameter, 'are placed in position over 
trees to be fumigated by means of so 
called '‘changing poles.” Larger tents 
are handled by means of uprights or 
derricks. The changing poles are light 
poles varying from 15 to 20 feet in 
length and attached to the tip of each, 
is a rope somewhat longer than the 
pole itself. Uprights or derricks are of 
simple construction, braced at the bot¬ 
tom to prevent them from falling side¬ 
ways, and provided with pulley blocks 
and ropes for raising the tent. Cypress 
is a very desirable material to use in 
making uprights on account of its 
lightness. Uprights are made from 25 
to 32 feet in length according to the 
size of the trees to be covered. They 
need be only within two or three feet 
of the extreme height of the tree for 
the uppermost branches readily bend 
forward when the tent is being pulled 
into place. 
The material used in the generation 
of hydrocyanic acid gas are Potassium 
cyanide (K C N), Sulphuric acid (H-2 
S O-4) and water. It is essential that 
the potassium cyanide be 98 or 99 per 
cent, pure, and that the acid show a 
gravity test of 66 degrees. The pro¬ 
portions of these materials used in gen¬ 
erating the gas are, one part of the 
cyanide, one part of acid (liquid meas¬ 
ure) and from 3 to 4 parts of water. 
The commissary consists of a mov¬ 
able table provided with balances for 
weighing the cyanide, a large stock 
pitcher for the acid, a measuring glass 
graded for fluid ounces, rubber gloves 
for the man who measures the acid, 
and a tin scoop and leather gloves for 
the man who weighs the cyanide. The 
generator tray is placed on top of the 
commissary table while “weighing up.” 
It is made with a removable upper 
rack for convenience. The upper rack 
contains two rows of tin cans for hold¬ 
ing the cyanide. Directly below each 
can in the lower rack or body of the 
tray is a pitcher for holding the acid 
for the given tree. The gas is gener¬ 
ated in earthernware jars of a capacity 
of from one and a half to three gallons 
according to the size of the tree. For 
large trees, two generator jars are fre¬ 
quently used. 
PROCEDURE. 
The systematic arrangement of de¬ 
tails is of great importance in fumiga- 
