180 MAGNESIA AS AN ANTIDOTE FOR ARSEN10US ACIDS. 
hitherto employed, of being always on sale at every che- 
mist's shop, that it readily and entirely neutralizes the poi- 
son, that a large amount may be administered without in- 
convenience, and that its general therapeutic effects are of 
themselves in relation with the indications to be fulfilled in 
such cases of poisoning. 
6. That magnesia decomposes tartar emetic, salts of cop- 
per, and corrosive sublimate ; and there is reason to believe 
that it might be employed with success in combating and 
mitigating the [effects of those poisonous substances, and 
that of metallic salts in general. 
7. That the salts of the organic alkalies, morphine, strych- 
nine, &c, being equally decomposed by magnesia, the use 
of this substance in cases of poisoning by organic products, 
whose action is owing to the presence of some vegetable 
alkaloid, might retard and render the absorption of the poi- 
son more difficult. This, however, I intend to confirm by 
subsequent experiments. — Chem. Gazette, from Comptes 
Bend us. 
Note. — The observations of M.Bussy, with reference to 
the use of magnesia as an antidote for several metallic poi- 
sons, are of the very first importance, should they prove to 
be substantiated in practice. Sofarasarsenious acid is con- 
cerned, I have tried several careful experiments, and have 
arrived at the conclusion that magnesia, like peroxide of 
iron, is only suitable as an antidote when it is in a hydrated 
gelatinous condition. A solution containing one grain and 
a half of arsenious acid was mixed with 30 grains of com- 
mercial calcined magnesia, of ascertained good quality, and 
frequently agitated. After several days the filtered solution 
yielded abundant green and yellow precipitates with the am- 
monio-sulphate of copper and the ammonio-nitrate of silver. 
The same quantity of Henry's or Husband's magnesia was 
then tried without removing the poison in 24 hours, (after 
which period it was not tested.) The quantity of magnesia 
was then increased to 80 grains, which, after a period of an 
hour or two, had precipitated the arsenic. When, however, 
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