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in shallow iron pans over a slow fire with constant agitation of the 

 grain, or by exposure on sheets or canvas to the rays of the sun. 

 This mixture may be made much more efiicient by the addition of 

 cyanide of potassium in the proportion one-half of 1 per cent. Pois- 

 oned grain has not been found efficient in the destruction of rats, as 

 its bitter taste causes them to eat Uttle or none of it. It is, however, 

 particularly efficient in poisoning squirrels, as it is taken readily by 

 them. The chief objections to its use are its cost, difficulties of 

 preparation, and hability to its being taken by chickens. 



CARBON BISULPHIDE. 



Carbon bisulphide is not a poison so much as an asphyxiant. As 

 the name indicates, it is a two-to-one mixture of sulphur and car- 

 bon. The resulting hquid preparation should be kept in air-tight 

 cans, since it evaporates quickly. The principle of its efficacy against 

 rodents is that the fumes are heavier than air and, sinking into a rat 

 or squirrel hole, drive out the necessary oxygen. To use bisulphide 

 saturate a small pad of some absorbent cotton, jute, wool, or flannel 

 material with the liquid, thrust this into the rodents' burrow, and 

 carefully stop all apertures through which the fumes might escape. 

 Animal hfe of every sort in that burrow is quickly asphyxiated. In 

 buildings the use of carbon bisulphide is greatly hampered by the 

 difficulty to confine the gas by stopping all cracks and other openings. 

 Also the odors of decomposition in animals so killed stand against 

 its use anywhere but in the country. 



Against rats and squirrels in country places carbon bisulphide 

 has proved one of the best of all weapons. Where it kills, it kills 

 whole families at a time, not one by one, as must ever be the case 

 with other poisons and with traps or shotguns. Not only does it 

 kill the rodent but it also destroys the rodent's fleas and vermin, 

 which is most important. A dead infected rat is still a menace, 

 since its fleas may inoculate other rats and human beings with the 

 infection. Destroy the fleas and that greatest danger is removed. 

 The recent campaigns against rodents in the United States have been 

 waged because rats and squirrels were infected with bubonic plague; 

 hence the added value of carbon bisulphide. Unfortunately, 

 though this asphyxiant proved so effective in the work against 

 squirrels in Contra Costa County, Cal., it proved to be well-nigh 

 useless during the summer season when dry heat checks the adobe 

 and makes the ground generally porous. Nevertheless, the value 

 of carbon bisulphide, especially for sanitary purposes, can not be 

 easily overestimated for work in the country during the fall, winter, 

 and spring seasons. 



Fumigants in general are effective. They possess no marked or 

 pecuHar advantages as special weapons against rodents. Their use 



