CHAP. Will. | PES - RED PRODI 



of not more than two pounds weight each, and placed ready in each 

 . the packets being allotted to different parts of the room 

 if more than one is required tor each room. The water is then 

 measured out and poured, tor each packet, into suitable gener; I 

 which should be sufficiently deep and be made of earthenware and 

 not of metal. The acid, also measured in each case, is then slowly 

 and carefully poured into the water. The acid must always be 

 added to the water and never the water poured into the acid, as in 

 the latter case violent action takes place and the acid is almost 



in to spatter about with possibly dangerous result- to 

 operator. For it must be remembered that sulphuric acid is a 

 strong corrosive. The water and acid may be mixed in the rooms 

 where they will be required finally if these have cement or stone 

 rs ; Otherwise it is better to mix elsewhere to avoid damage to 

 flooring should the acid spill or boil over on being added to the 

 water. The acid and water and the packets of cyanide being all 

 ready, and all doors except those actually required for access to 

 the rooms being closed, and all persons except the operator being 

 outside the building, the operator commences at the top of the 

 building, drops the packets of i generators 



and immediately leaves that room, repeating the operation on the 

 next tloor below and so working downwards, carefully and rapidly, 

 to the groundfloor and out by the door which is then carefully 

 closed and locked from the outside. If there are two or more rooms 

 ich floor it is useful to have one or more intelligent assistants 

 it all the rooms on each floor may be treated simultaneously. 

 If the cyanide is made up in paper packets the acid will take a 

 short time to get through the paper, thus giving a few seconds in- 

 terval between the dropping of the packets into the generators and 

 the ebullition of the gas. which will be enough to secure a 

 retreat. Fumigation l>\ Hydrocyai >, if properly carried 



out, is a radical cure for all living animals (beetles, larva;, bugs, 

 Hies, fish-insects, rats and mice) in the building treated, but it 

 should only be carried out under strict supervision of a competent 

 operator. The building should be left closed for twenty-four 

 hours, after which doors and windows may be opened from the out- 

 side a- far as possible and left open for at least an hour to permit 

 the . pe. No attempt must be made to enter the building 



if any smell of gas is still perceptible; this smell is faint and some- 

 thing like that of peach-kernels or of some metals when these are 

 struck together. 



In colder countries successful results in the control of grain pests 

 in flour mills, etc., have lately been attained by the US 



i"-ing laid down in the rooms and steam 



