TOXICITY OF BARIUM CARBONATE TO RATS. 9 



tration is then readily comprehensible. In case of 20 per cent barium 

 carbonate in the bait, it is necessary for the rats to consume only 

 one three-hundred-and-twcntieth to one two-hundred-and-sixty-sixth 

 of their body weight, or 31 to 37 per cent of the average food intake, 

 in order to ingest a lethal dose of barium carbonate. As a few will 

 fail to do this and many eat much more, this concentration is efficient, 

 as well as quickly fatal. 



RESULTS OF EXPERIMENTAL WORK ON OTHER BARIUM COMPOUNDS. 



Barium chromate was found to be nontoxic in doses as high as 

 2,000 mg. per kilo. 



Barium soap, chiefly palmitate, was fairly toxic. Although not 

 enough experiments were performed to definitely fix the lethal dose, 

 it would seem to be approximately equal to that of barium carbonate. 

 Its ease of hydrolysis apparently would favor the mobilization of the 

 barium, upon which basis it would be more desirable than the car- 

 bonate. This fact, however, precludes its use in rat bait, since the 

 hydrolysis occurring from a small amount of moisture would impart 

 a disagreeable taste. 



TOXICITY OF BARIUM CARBONATE TO ANIMALS OTHER THAN RATS. 



Apparently rats are about as susceptible to barium administered 

 subcutaneously as rabbits, chickens, and pigeons, and approximately 

 one- third as sensitive as cats and dogs. When the barium is ad- 

 ministered by mouth, however, the rat is comparatively the least 

 susceptible of all the mammals cited, although the absolute amount 

 is less, because of the small size of the rat. 



If 20 per cent barium carbonate is used, it will be possible, on the 

 basis of the recorded doses of barium chlorid, for adult animals to 

 eat without fatal effects the following amounts of this rat bait: 

 Sheep, one-half ounce; horses, 1J ounces; and cattle, 5 ounces. Pre- 

 sumably, one and a half times this amount could be borne, since barium 

 carbonate is less toxic than the soluble chlorid. The lethal dose of 

 barium carbonate for chickens (20) is 20 grains, or one-fifth ounce, 

 of rat bait containing 20 per cent of this poison. The danger to man, 

 particularly children, is so very great that an amount of bait set for 

 one or two rats might prove fatal. 



CONCLUSIONS. 



The lethal dose of barium compounds for rats is as follows: Barium 

 chlorid, subcutaneously, 45 to 89 mg. per kilo; barium chlorid, by 

 stomach tube, 350 to 535 mg. per kilo; barium carbonate, per os, 

 630 to 750 mg. per kilo. On the basis of the barium content, the 

 carbonate is about two-thirds as active as the chlorid per os. 



