CYANIDING. 53 



downwards immediately the trigger, H, is pulled away, 

 and so that when the bottle is tipped over as far as it will 

 go the other way it will remain in that position for filling, 

 etc. A button, F, is. put on of isuch a length that when 

 it is. turned down, as in the sketch, the bottle will not 

 remain at rest, but must pitch forward and empty its 

 contents. The screw^s, G, go into slots cut in the two 

 uprights, B, which are nailed to a piece of board, A. 

 The trigger, H, is simply a small strip of wood long enough 

 to reach from the ground to the punkah, and having a 

 nail driven through it to act as a support to the platform, 

 C, when the apparatus is set. 



"A Word of Caution — There are a few remarks to 

 be made about the process before concluding. Sulphuric 

 acid, when diluted, must always be poured into the water, 

 for if the water is poured into the acid it will probably be 

 distributed about the operator's person in a way he is not 

 likely to forget. When opening the ventilators to allow 

 the gas to escape, keep to windward, and hold the breath 

 until you are at a safe distance, and do not enter the 

 houses until half an hour has passed. Eemember that 

 the temperature must be low and the leaves of the plants 

 dry, or damage will result. Experiment first with small 

 doses, and gradually increase until the pests are killed. 

 Mr. Strawson has found the following strengths effica- 

 cious: l^oz. of the 130 per cent, cyanide per 2,000 cubic 

 feet sufficient for easily-killed insects; and from 2oz. for 

 some others, up to 3Aoz. for lied Spider." 



