734 



The Destruction of Rats. 



[DEC, 



better be obtained by experience than by description. As 

 regards traps, the spring trap which kills the rat at once when 

 the spring is released is the best, but care must be taken to see 

 that no other animal is caught, and traps should therefore be 

 visited frequently. Another kind is the wire trap, on the 

 eel-basket principle, which the rat can enter easily when 

 attracted by the bait but cannot leave. 



Rat poisons are sold in all country towns by chemists, and 

 several patent or proprietary poisons are advertised in agricul- 

 tural and other newspapers. They are generally" composed 

 of phosphorus paste or arsenic, but strychnine may also be 

 employed, while the use of barium carbonate has also been 

 recommended.* Plaster of Paris is sometimes used mixed 

 with flour, which sets into a hard mass in the rat's stomach. 

 It must be remembered that rats are very suspicious, and if 



* A recent bulletin published by the United States Department of Agri- 

 culture discusses the relative merits of arsenic, phosphorus, strychnine and 

 barium carbonate as rat poisons. Arsenic is cheap, and perhaps the most 

 popular poison for the purpose, but experiment showed that, measured by the 

 results obtained, it is dearer than strychnine. It is variable in its effects. 

 One part of arsenious acid may be mixed with twelve parts by weight of oat 

 or maize meal and made into stiff dough with white of egg. Phosphorus is 

 almost as commonly used as arsenic, and is effective when mixed in an attrac- 

 tive bait ; but in the paste forms, which contain from one to four per cent, 

 of yellow phosphorus in glucose and other substances, the lower percentage 

 is too small to be always effective, and the larger amount is dangerously 

 inflammable. Many fires have been caused by phosphorus paste in the United 

 States, and the Biological Survey does not recommend its use. It is said that 

 there is no foundation in fact for the statement that phosphorus dries up or 

 mummifies the body without odour when eaten by rats or mice. Strychnine 

 may be effectively employed in the open and round farm buildings, but it is 

 too rapid in its action for use in houses, as the vermin would die on the 

 premises. Dry crystals of strychnia sulphate may be inserted in portions of 

 raw meat, sausage or fish, and these placed in the burrows. Strychnine syrup 

 may be prepared by dissolving ^ oz. of the sulphate in one pint of boiling 

 water and stirring in one pint of thick sugar syrup ; this may be used to 

 moisten a bait of oatmeal, while wheat or maize may also be soaked in it. 

 In all cases it is advisable that baits containing one of the aboveypoisons should 

 be obtained ready prepared from a pharmaceutical chemist. Barium carbonate 

 is considered one of the cheapest and most effective poisons for rats and mice. 

 It is without taste or smell, has a corrosive action on the mucus lining of the 

 stomach, and, causing thirst, induces the vermin to seek water in the open, 

 where they die. In the small doses used it is said to be harmless to domestic 

 animals. It may be employed in the proportion of one part of the carbonate 

 to four parts of meal, mixed to a dough with water. A convenient bait is 

 composed of one part by measure of the mineral to eight parts of oatmeal, 

 mixed to a stiff dough. The carbonate may also be spread on fish or moist 

 toasted bread. In 1905 large quantities of a poisonous food were sent out by 

 the Agricultural Botanical Institute at Munich for the purpose of destroying 

 field mice, and it is stated that it chiefly contained barium carbonate. 



