APPENDIX TO PAET 11. 



ANTIDOTE TO ARSENIC. 



The following is from a letter of Samuel L. Dana, M. D., 

 of Lowell, to Dr. Bartlett, published in the ** Boston Daily 

 Advertiser." August 3d, 1842. 



** According to the experiments of M. Guibourt, white ox- 

 ide of arsenic, (or white arsenic) digested with hydrated 

 peroxide of iron, forms a compound, whose proportions 

 differ from that of arsenite of iron, by containing a larger 

 portion of iron. It is this salt, which forms in the stomach, 

 when peroxide of iron is administered as an antidote to 

 arsenic. It contains 3| times as much iron as arsenic. It 

 is perfectly insoluble and innocuous. Three things are 

 essential to the action of this antidote. 



** 1st. Perfect freedom from protoxide of iron. 



**2d. Perfect freedom from free alkali, or alkali com- 

 bined with the oxide of iron. 



**3d. It must be freshly prepared without drying. 



** 1st. If the antidote contains protoxide of iron, then 

 that combines with the arsenic and forms a compound 

 which, though of sparing solubility, is yet poisonous and 

 prevents the ulterior good action of the peroxide of iron. 

 A mixture of prot and peroxides of iron is no antidote to 

 arsenic. 



*' 2d. If carbonate of potash is used to precipitate a solu- 

 tion of persalt of iron, a portion falls, combined with alka- 

 li. Hence Berzelius recommends bicarbonate of potash, 

 cold, to be used for this purpose. The effect of alkali, 

 free, or thus combined with peroxide of iron, will be, to 

 form soluble poisonous arsenites as above noticed. 



*'3d. The effect depends on the antidote being freshly 

 prepared. I would therefore, in order to insure the 2d 

 and 3d conditions, recommend the solution of pernitrate of 

 iron to be taken dilute, followed by aq. am. and wet by a 



