MAGNESIA AS AN ANTIDOTE TO ARSENIC. 
287 
analogous compound was not formed, but the hydrate of 
the oil of turpentine with 1 equiv. water. The bodies ex- 
amined are therefore combinations of oil of turpentine with 
1, 4 and 6 equivs. water, and with 1 equiv. muriatic acid.— 
Chem. Gaz.from Jinn, der Chem. and P harm. 
ART. LXI1L— OBSERVATIONS ON MAGNESIA AS AN ANTI- 
DOTE TO ARSENIC. By Dr. Christison. 
Dr. Christison's attention was lately turned to this subject 
by a case of poisoning with arsenic having come under his 
notice, in which magnesia seemed to prove very service- 
able. Immediately afterwards he observed it announced 
in a French scientific newspaper, 'L'lnstitut,' May 20, that 
a paper had been read before the French Institute two 
days before by M. Bussy, to prove, "That magnesia, not 
strongly calcined, removes arsenic entirely from a state of 
solution in water; that this is effected still more completely 
by magnesia in the gelatinous state ; and that animals which 
have taken arsenic are invariably saved if made to swallow 
magnesia." While waiting for the details of M. Bussy's 
inquiries, Dr. Christison made a few experiments to ascer- 
tain the amount of the action of magnesia ; and he found 
that the dense magnesia of the shops exerts very little ac- 
tion in removing arsenic from solution in water; that a 
very light magnesia, now largely manufactured at Belfast, 
and quite free of carbonic acid, will remove about a 
twenty-fifth of its weight of arsenic from solution in water, 
when agitated with the solution for a few minutes; so that 
even ammoniacal nitrate of silver does not any longer indi- 
cate the presence of arsenic ; that the same magnesia will 
remove about a twelfth of its weight of arsenic if agitated 
