172 PROCEEDINGS OP THE AMERICAN ACADEMY. 



poisoning by potassic arseniate,* the chemical tests show the sub- 

 stance to have been an arsenite. 



The difference in action between arsenious and arsenic acids was first 

 studied by Wohler and Frerichs | in 1848, arsenic acid previous to 

 that time having been considered more poisonous than arsenious acid. 

 They concluded that the arsenic acid was less active than the arseni- 

 ous, following the analogy of the phosphoric and phosphorous acids. 

 They thought that the arsenic acid was reduced in the organism to 

 arsenious acid. They also proved the poisonous quality of calcic 

 arseniate, although it is insoluble. This is also shown by Schmidt and 

 Bretschneider.J Schroff,§ in 1852, experimented more carefully than 

 Wohler and Frerichs, and came to the conclusion that arsenic acid 

 was not very much less poisonous than arsenious acid. Marme,|| 

 in 1875, quotes Savitsch,H who found that the poisonous qualities 

 stood in the same ratio as the percentage of metallic arsenic in each. 

 Marme, however, in a carefully conducted series of experiments, was 

 able to show that arsenic acid is much the less energetic. Reichardt** 

 remarks the necessity of determining the state of the arsenic, in order 

 to know whether it is injurious or not. He considers that arsenic acid 

 may be combined with iron in ochres, and supposes ferric arseniate to 

 be harmless. Yet if calcic arseniate is poisonous, why not ferric ? 



If arseniates are less poisonous in large doses, is it because they are 

 less of an irritant? If less irritating, could they be accumulated more 

 easily if in minute doses ? 



This leads to the consideration of the localization of arsenic in 

 chronic cases. Scolusuboff,ft in 1875, found the deposition, when taken 

 as arsenious oxide and sodic arsenite, to be chiefly in the brain, " from 

 which it is carried by the circulation to other organs." Lud\vig.$J in 

 1881, finds this assertion to be wrong as far as arsenious oxide is 

 concerned, the brain containing comparatively little, while the liver con- 



* Bouley, jeune, Mem. Acad. Roy. de Med., Paris, 1835, IV. 298-307. 

 t Ann. d. Chem. u. Pharm., LXV. 345. 

 \ Molescliott's Untersuchungen, 1859, VI. 146. 

 § Archiv f. pliys. u. path. Chem. u. Mikr., Wien, V. 241. 

 || Nachr. v. d. kunig. Gesells. d. Wissens. a. d. Georg. Aug. Univ., Gottingen, 

 1875, p. 614. 



IT Dissertation, Dorpat, 1854. 

 ** Loc. cit. 



tt Archiv de Phys. norm, et path., 1875; also, Ann. d'Hygiene publ. et de 

 Med. le'gale, Jan., 1876. 



tt Jour, de Pharm. etde Chemie, [5], VI. 198 ; also, Chem. Centralblatt, 1881, 

 p. 90. 



