246 
MINUTE DIVISION OF MERCURY. 
riably the case when the extract is of that hard and tenacious 
consistence in which it will retain its form when made into 
pills. If it be only the oxide which exerts an influence on 
the system, this separation of the pure metal is unimportant, 
excepting inasmuch as it proves that the preparation is im- 
perfect ; and if a portion of the mercury be oxidized by tri- 
turation with the chalk, we may infer that the whole might 
be so oxidized by continuing the trituration, since all the 
metal is exposed to the same treatment. But we know by 
experience that the process may be continued for weeks or 
even months without reducing the preparation into a state in 
which metallic globules cannot be separated from it ; there- 
fore, on the supposition that the oxide alone possesses any 
virtue, a mixture of that substance with chalk would make a 
more efficacious compound, and black wash, as an internal 
remedy, might be substituted for a preparation which, by the 
hypothesis, must be defective. 
But we know that in the case of the unguentum hydrargyri 
this substitution of the oxide for the metal is quite inadmissi- 
ble, as the ointment made with the oxide leaves the mercury 
on the surface of the skin, while the other ointment is absorb- 
ed. It may be the case that a portion of the mercury exudes in 
globules, and escapes unobserved during its application, but 
the facility with which ptyalism is produced by mercurial 
frictions, is a sufficient proof that a considerable portion of 
the metal enters the system. Although we cannot have 
ocular demonstration of this assimilation of mercury when 
taken inwardly., we may infer that the absorption of the metal 
may take place when applied to the coats of the stomach and 
other tissues in a finely divided state. It is not unlikely that, 
when thus divided, it may be capable of oxidation, during its 
passage through the alimentary canal, and in this state com- 
bine with the acids which it may meet with, forming com- 
pounds more or less active, and thus producing as much 
medicinal effect as it would have done if administered in the 
form of an oxide. 
A single dose of blue pill will sometimes act as a purgative, 
