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the old homes to the new. A new disinfestation depot was built at Wood Lane in the same grounds
as the disinfecting station, and two vans, built to the specification of Imperial Chemical Industries,
were purchased.
The vans are a modification of the type used by railway companies for their door-to-door
transport service, and are of all-welded steel construction, with a sliding door on one side. There is
a recess at one end, and in this recess are placed the vaporiser (which is in effect an electric kettle)
in which the cyanide is boiled, and an outlet to an exhaust fan. In the vans there are electric gastight
tubular heaters, for it has been found that the gas is more effective when applied in a heated
compartment. The necessary electric connections are made at the recess. The vans, which are
14 ft. by 6 ft. 6 in. by 6 ft. 8 in., are placed on chassis conforming to the latest traffic regulations
for road vehicles. In order to ensure safety, the vans are made to withstand great pressure.
The station consists of a dutch barn constructed over a concreted site. At one end of the barn
there is a 9-in. pipe connection to a fan and a tall chimney, with 3-in. pipe connections and valves
to each van. There is also the electric switchboard which carries the current to the vans for heating
purposes. In the middle of the barn there are rails on to which the vans are rolled for fumigation.
When the loaded vans arrive at the station, the bedding is removed and is taken to the steam
disinfector for treatment. The tight-fitting door is then closed and the heaters in the van are
switched on. The vaporiser is filled with the requisite amount of cyanide and is heated by an
electric hot plate fitted under its base. The cyanide evaporates completely in about 15 minutes
and the gas is conducted straight to the interior of the van, which is allowed to retain its charge for
two hours. At the end of this time an outlet-valve is opened and the exhaust fan is set in motion,
thus sucking the gas in the van up a chimney into the open air. The van is cleared of a dangerous
concentration of gas and the door is opened. Chemical tests are applied to prove the absence of
gas. The compartment is then allowed to air naturally for some time before the furniture is
conveyed to the new home. The collection, fumigation and subsequent clearance and delivery
take about eight hours.
It is essential that only skilled men should handle this gas, and therefore one sanitary inspector
and two members of the disinfecting staff were sent to the cyanide plant of Imperial Chemical
Industries at Billingham, Stockton-on-Tees, where they underwent a comprehensive course of
instruction in the handling of hydrocyanic acid, van fumigation, first aid, and the use of resuscitation
apparatus.
During fumigation, two trained men are always present, and they work under the supervision
of the sanitary inspector. A man is never allowed to be alone during the application of the gas
or when the doors of the van are being opened.
From the first week in July to the end of the year the furniture of nearly 400 families was
fumigated in connection with clearance and improvement area procedure, and it is significant that
only four of the loads were found to be entirely free from vermin.
All the effects of every family moving to a new dwelling are fumigated. Tenants are given
notice of removal some weeks before the scheduled date, so that they can wash the furniture, thus
facilitating the work, and make other necessary preparations. There has been no difficulty in getting
the tenants to co-operate in the scheme ; the fact that their furniture is removed free of charge is
undoubtedly a great encouragement.
On the day appointed for removal the van reaches the old home early in the morning, and the
men collect everything the family wish to take to their new home. The furniture is delivered clean
in the afternoon, so that there is the minimum of inconvenience to the people concerned. During
the year there were only six claims for damages, and these were met by a total payment of 35s.
The cost of fumigation, including transport charges, insurance, etc., is approximately £3 per
load. It should be pointed out, however, that in many cases the effects of two families are fumigated
in one van, and the cost per family is therefore less than £3.
The system of van fumigation has been highly successful, and up to the present there has been
no recurrence of vermin in the new homes. It may be interesting to note that there is an arrangement
whereby people who wish to buy second-hand furniture, etc., may have such articles fumigated
before taking them to new homes. The response to this arrangement has been very encouraging,
and it is evident that people, when given a clean start in a new home, are anxious to live up to a
standard which is considerably higher than their former one.
The Treatment of Verminous Dwellings.
The question of fumigating verminous dwellings is beset with difficulties. Several houses have
been treated with hydrocyanic acid gas. One experiment of great interest may be mentioned,
namely, the fumigation of Hope Cottage, Alderson's Yard, Kensal Road, early in 1934. This house,
which is entirely detached, was treated with hydrocyanic acid gas by a new method. Arrangements
were made to accommodate the tenants elsewhere for a day and a night, and they left their home
by 9 a.m. The house was securely sealed except for two windows and the front door. Through
these windows hot air was pumped by the Dreymura Tubit drying system. A uniform temperature
of 100° F. was reached in a short time. Hydrocyanic acid was then placed in the rooms in the form
of Zyklon B, which is a granular diatomaceous earth impregnated with cyanide. The gas is given
off as soon as the earth is exposed to the air. Immediately the gas was released the hot-air supply
was shut off and the sealing of the house was completed. The house was left under the gas for four
hours, after which all windows were opened and the heating apparatus was again put into operation.