CO885-(20-21) — Page 663

J

52.

C is piece of wick passing through the wick holder with the end outside hanging down over the water, and that inside lying at the bottom of the barrel.

Crude Oil

D

Larvicide

53

the services of one or two, as the oil may be carried in a tin knapsack arrangement.

Method-The mixture used is :—

Crude oil, 5 gallons (cost 12 c.). Pure kerosine, 1 gallon (cost 7 c.). Total cost, 19 c. (9§d.).`

square

feet.

This is enough for about 250 The mixture is placed in a barrel from which it is pumped by a double pump, one part of which takes up the mixture and another air, and then forces them mixed together along a hose which ends in a metal tube about 12 feet long with a sprinkler at its tip as in the spray. Around this a piece of tin is fixed as in diagram.

A

D

PUBLIC RECORD OFFICE

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Reference -

C.O. 885

21 PUBLIC RECORD OFFICE, LONDON

ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH-NOT TO

Larvicide is put into the barrel up to the point D, and covers the inner end of the wick, and the barrel is then filled up with the crude oil.

The barrel is supported on bars over the water, and the oil drips

on to its surface, the rate of drip being regulated by opening or compressing the tin wick holder.

The larvicide thins the oil in passing along the wick.

If the wick gets blocked it must be syringed with larvicide. Kerosine tins are also used as drippers.

A hole is made in the bottom of the tin with a nail, and a strand of oakum passed through it so that one end hangs outside. Crude oil is put in the tin, which is suspended over the water, and the rate of drip depends on the tightness with which the oakum fits the hole.

130. Spraying.--Spraying is done by means of a hand spray; the cost of which is about $10.

Meyer's

A man carries a tank of oil slung on his shoulders just like a knapsack, and with one hand he works the pump and with the other directs the spray.

If the oil is too thick it is diluted with larvicide as required. This spray gives very satisfactory results, is much better and more convenient than those at present in use in Lagos, and only requires the labour of one inan.

131. Spraying and burning.--This method is being introduced for treating edges of streams and drains, and when properly carried out keeps the growth down for a very long time.

The first time it is done very thoroughly, and four men are required, but later burnings only necessitate

The oil and air mixture is pumped along the tube A through the sprinkler B, the flow being regulated by the tap C.

Spray impinges on a small dise D which is fixed in an inverted metal cone which covers the sprinkler, and which is thought to divide the spray better, and give more opportunity for vaporisation.

The

A little oil is first sprayed on the grass and fired. end of the tube is put into the flames and the pump worked. The fire heats the sprinkler and inverted and

cone, instead of the oil dropping down, it volatilizes and burns, and very soon, then continues to burn. A large flame is made, which is regulated by the supply, and is directed on the grass and weeds by the man holding the metal tube. By this means the grass, roots, &c., are burnt, and the land sprayed.

For future burnings a less heavy apparatus is being introduced. The iron tube is shorter, of a lighter character, passed through a piece of bamboo cane to keep it cool, and wrapped in asbestos for the last foot to prevent the wood burning.

A single-nozzle sprinkler is found to give better results than a double or treble one.

132. Edges of all streams and cut drains are cleared at intervals and sprayed with oil, but the method of firing and spraying described above will simplify this, be less expensive, and more lasting.