Examination of the Peroxide of Manganese. 81 



ger of introducing it in the apparatus, and moreover, the tests 

 already mentioned, are sufficient to enable us to distinguish be- 

 tween antimony and arsenic. 



I shall conclude what I have to say on this subject, with the 

 resume of the report of the Academy of Sciences. 



" The committee, resuming the instruction contained in this 

 report, think that Marsh's process, applied with all the precautions 

 which have been indicated, satisfy the demand of medico-legal 

 researches, in which the quantity of arsenic, which it is attempt- 

 ed to exhibit, is always much superior to that which the delicacy 

 of the apparatus exhibits ; (ttf nin o o ^^ arsenic acid existing in a 

 liquid, is about the extent of the delicacy of the apparatus.) 

 At the same time it must be well understood, that it is always 

 to be employed as a means of concentrating the metal, in order 

 to study its chemical characters, and that we should consider as 

 nothing, or as extremely doubtful, the indications which it fur- 

 nishes, if the deposit which is formed in the anterior part of the 

 tube, does not permit the experimenter, on account of its very 

 small quanity, to verify in a precise manner, the chemical charac- 

 ters of arsenic." 



" We will add that in the greater number of cases of poisoning, 

 the examination of the matter vomited, and of that which re- 

 mains in the intestinal canal, will convince the experimenter of 

 the presence of the poison, and that he will have only to proceed 

 to the carbonization of the organs, in cases where the first efforts 

 have been fruitless, or in those very rare cases, where presumed 

 circumstances of poisoning shall indicate to him the necessity." 



Paris, June 28th, 1841. 



Art. IX. — Remarks upon an examination of the Peroxide of 

 Manganese; by Henby C Lea. 



It is of great importance, both to the practical and theoret- 

 ical chemist, to have the combinations which the different me- 

 tals form with the acids, investigated, in order that the proper 

 degree of conlidence may be reposed in the various theories 

 which have been formed from time to time by so many celebra- 

 ted chemists. It is with this view alone that I consider these 

 examinations as worthy of being published, as I unfortunately 



Vol. xLii, No. 1.— Oct.-Dec. 1841. 11 



