REPORT OF THE ENTOMOLOGIST. hove 
the gas through sulphuric acid the leaden acid-vessel can be dispensed with, the 
leaden pipe from the generator passing directly into the tent.* 
Im charging the generator for the dry gas process, the proper quantity of the 
aa ang solution is poured into the lower vessel through the opening closed 
y the screw-cap, this cap having first been removed, to be again replaced after the 
solution has been poured in. The stop-cock connecting the two vessels of the gen- 
erator is next closed by turning the handle attached to the valve, after which the 
proper quantity of sulphuric acid is poured into the upper vessel, The tin pipe at- 
tached to the upper end of the leaden acid-vessel is then removed, and a slightly 
larger quantity of sulphuric acid is poured into this vessel than was poured into the 
upper vessel of the generator; there should be a sufficient quantity of the acid in 
this leaden vessel to slightly more than cover the end of the leaden pipe leading from 
the generator. The tin pipe is next attached to the upper end of the acid-vessel, 
as shown in Plate V, while the other end of this pipe passes into the tent pre- 
viously placed over a tree and made ready for the reception of the gas. 
When everything is ready the handle of the stop-cock of the generator is turned 
until the acid in the upper vessel commences to fiow into the lower one, where it 
comes in contact with the cyanide solution, and the production of the gas begins. 
The acid should be allowed to flow very slowly upon the cyanide solution; if the gas 
is produced too rapidly the acid will be thrown out of the acid-vessel; the latter 
should be taller than indicated in Plate V, and it would doubtless be an advantage 
to have it wider at the top than at the bottom. 
After all of the gas has passed into the tent, the acid in the acid-vessel should be 
emptied into a glass or leaden vessel to be used the next time for generating the gas; 
for this purpose it would be well to insert a brass stop-cock in the lower part of the 
acid-vessel. There should also be quite a large stop-cock in the lower part of the 
lower vessel of the generator, for drawing off the residue before again charging the 
generator with fresh materials, "When not in use the two vessels of the generator, 
and also the acid-vessel, should contain a small quantity of water, which will pre- 
vent the valves of the stop-cocks from becoming so corroded that they can not be 
operated without first being taken apart and cleaned. 
AGITATING THE AIR IN THE TENT. 
After the gas has passed into the tent, and also while it is passing in, the air in the 
tent should be thoroughly agitated. The most effectual method of accomplishing 
this is by the use of some device whereby the air may be drawn out of the top of the 
tent and forced in at the bottom. When the McMullen or the Culver tent is used, 
the pipe taking the air out of the upper part of it can enter the top of the tent, but 
in the Wolfskill and the Titus tents both pipes must enter the tent at the bottom, the 
one intended for drawing the air out of the upper part of the tent passing some dis- 
tance up the trunk of the tree, while the cther pipe merely passes a short distance 
into the tent. 
For circulating the air in the tent various devices have been used, but the one that 
has given the best satisfaction is known as the Cummin’s blower, which ‘vas orig- 
inally intended for forcing air into mines. It consists of an iron fan-wheel, driven 
with great velocity by means of a series of cog-wheels and pinions, the whole en- 
cased in an air-tight iron covering, having an opening on one side of the fan-wheel, 
through which the air is drawn out of the tent by means of a tin pipe, the base of 
which covers this opening. In the lower part of the fan-wheel chamber is a large 
opening, placed opposite to a similar opening in one side of an iron pipe closed at 
one end while to the other end is attached the tin pipe through which the air isto be 
forced into the tent. When the crank operating the fan-wheel is turned the air 1s 
drawn out of the tent through the tin pipe, and passes into the fan-wheel chamber 
through the hole in the side of the latter, and by the rapidly revolving fan-wheel 
is thrown by centrifugal force into the tent. 
I had a blower constructed upon nearly the same principle as the above, except 
that the fans were made of tin, as was also the covering of the fan-wheel chamber, 
but it did not give very good satisfaction. 
There is a machine manufactured at San José, Cal., and known as the Acme fu- 
migator, which is provided with an iron fan-wheel driven by a belt. The blower 
*Mr. Coquillett writes later as follows: “‘ In speaking of the gas generator Tree- 
ommend passing the gas through sulphuric acid; a better way is to pass it into the 
acid, the leaden pipe which conducts the gas from the generator entering the upright 
jJeaden vessel above its middle, and curving downward in the vessel until the mouth 
of the pipe nearly reaches the bottom of the vessel and is covered by the acid.” — 
