» 



70 



of lacking taste or odor; that it has a corrosive action on the 

 mucous membrane of the stomach if taken in sufficient quan- 

 tity; that in the small doses fed to rats and mice it would be 

 harmless to other animals, and that its action upon rats is slow, 

 so that if possible they usually leave the premises in search of 

 water. This would appear to be the best rat poison known,^ 

 but Dr. Rucker of the Public Health Service says : — 



Tliis has not proven an effective poison owing to the fact that it is 

 easily decomposed by the vegetable acids, especially lactic and oleic 

 acid found in cheese and oil. The poisonous effect is not greatly altered 

 by this change. A disagreeable metallic taste is produced and the rats 

 will not take it.^ 



In the experiments conducted by the Massachusetts State 

 Board of Agriculture, rats rarely took this poison, and when it 

 was given to others to try, they reported that rats gave it "the 

 absent treatment." Although they were first fed food prepara- 

 tions without the barium carbonate, they would not touch them 

 after the barium had been incorporated. 



Professor Lantz finds this poison effective when prepared as 

 follows: ■ — 



Barium carbonate may be fed in the form of dough composed of four 

 parts of meal or flour and one part of the mineral. A more convenient 

 bait is ordinary oatmeal with about one-eighth of its bulk of the mineral, 

 mixed with water into a stiff dough. . . . The prepared bait should be 

 placed in rat-runs, about a teaspoonful at a place. If a single apphca- 

 tion of the poison fails to kill or drive away all rats from the premises, it 

 should be repeated, with a change of bait. 



Rod well recommends the following: take a quarter of an 

 ounce of the powder. Make it up, with two ounces of flour or 

 meal, into little balls, like marbles. The addition of two drops 

 of oil of anise seems to make it more attractive to rats, but not 

 to mice.^ 



One difficulty in regard to procuring barium carbonate is that 

 most drug stores apparently do not carry it, and some druggists 

 are likely to "palm off" barium sulphate upon the purchaser, 



1 Lantz. David E., U. S. Dept. Agr., Biol. Surv. Bull. 33, pp. 44, 45. 



' Treas. Dept., Public Health and Marine Hospital Serv. of U. S., The Rat and its Rela- 

 tion to the Public Health, by various authors, 1910, p. 157. 

 ' Rodwell, James, The Rat, 1858, pp. 261, 262. 



