Means of detecting Arsenic in the Animal Body, 6fc. 279 



1st. Does the hydrated peroxide of iron contain arsenic ? 



2d. Does arsenic exist normally in the animal tissues ? 



3d. Is not Marsh's apparatus subject to serious objections ? 



4th. What are the best means not only of detecting but of 

 ascertaining the quantity of arsenic when in combination with 

 animal matter ? 



5th. What are the best means of combatting the poisonous 

 eifects of arsenious acid ? 



To all these questions such answers will be given as have yet 

 been furnished. 



Does arsenic exist in the peroxide of iron 7 



This question originated from the fact that this substance had 

 been administered in the case spoken of; and there are those who 

 suppose that the arsenic detected belonged originally to the per- 

 oxide of iron used as an antidote. 



It is well known that arsenic exists in a state of combination in 

 many of the sulphurets of iron, from which the sulphate is ob- 

 tained, and it is the latter that furnishes the peroxide either by 

 precipitation or heat. Both forms of this oxide have been sub- 

 jected to minute examination by M. Orfila, who was particularly 

 interested in this question, and the following are his experiments 

 with their results : 



" 1st. I boiled during four hours, in five capsules, four and 

 a half ounces of hydrated peroxide of iron, taken from different 

 apothecaries, with four ounces of distilled water, and by Marsh's 

 apparatus no trace of arsenic could be obtained. 



" 2d. I then added thirty grains of pure caustic potash to the 

 hydrated peroxide of iron in each capsule, but no trace of arsenic 

 could be obtained. 



" 3d. But on treating by an ebullition of five hours an equal 

 quantity of hydrated peroxide of iron in pure sulphuric acid, the 

 liquid of three capsules out of the five gave arsenical taches. 



" 4th. Four portions of four ounces each of colcothar of com- 

 merce, (the anhydrous peroxide of iron formed by heating the 

 sulphate,) obtained from different merchants, by ebullition for 

 four hours in distilled water, did not give indications of the pres- 

 ence of arsenic. 



" 5th. This substance in the same quantity by ebullition du- 

 ring five hours with strong sulphuric acid, gave large arsenical 

 taches with the aid of Marsh's apparatus. 



