GOLD-DUST AND IRON-FILINGS AS ANTIDOTES. 335 
cury is at once revived, and will be seen to precipitate in a 
state of amalgam with the gold: at the same time, the oxygen 
from the corrosive sublimate goes over to the iron, and forms 
an oxide of that metal, with which the chlorine combines, 
leaving a hydrochlorate of iron in solution. The products of 
this decomposition are wholly innocuous, the amalgam of the 
two metals being entirely inert, and the hydrochlorate of iron 
possessing only the properties of a slight tonic. Two grains 
of gold and two of iron are sufficient to decompose five grains 
of corrosive sublimate, so that no trace of mercury can be 
detected by the most delicate test. 
In order to insure a rapid decomposition of the salts of 
mercury, it is important that both metals should be in the 
minutest state of division. The iron we made use of was re- 
duced almost to an impalpable powder, by working a piece of 
steel with the finest file. The gold can be procured at all 
times, in the state of bronze; as this is liable, however, to im- 
purities, it is better to have it prepared expressly for the pur- 
pose, in the ordinary way of reducing it to powder, or by 
filing. Gold-leaf may also be used. Both metals should be 
so minutely divided, as to be capable of suspension for a short 
time, in any fluid, and form, when agitated in water, as it were, 
a gold and iron solution. For it is the galvanic action excit- 
ed at the moment, that each particle of one metal comes in 
contact with a particle of the other, that the corrosive fluid 
immediately surrounding them is decomposed; and hence, in 
order to render rapidly innocuous a considerable bulk of a so- 
lution of corrosive sublimate, it is important that both metals 
should be as widely and intimately diffused in it as possible. 
This method of decomposing the bichloride, applies with 
equal force to all the more soluble compounds of mercury for 
which no antidote has yet been suggested. The deuto-iodide 
of mercury in water, is instantly deprived of its bright ver- 
milion lustre, on the addition of gold and iron, and a gray preci- 
pitate, composed of an insoluble iodate of iron and an amalgam 
of gold and quicksilver, is the result. If we take the peroxide 
of mercury, (red precipitate, red oxide of mercury,) and 
