242 
MINUTE DIVISION OF MERCURY. 
" During the trituration a small quantity is converted into the 
protoxide, and the remainder is mixed with the chalk in a 
state of very minute division." 
Dr. Duncan, in 1830, differs from both, and gives, as a pos- 
sibility ', a statement which he had, in the year 1816, asserted 
as a fact : 
Pil. Hydrarg. ( Dr. Duncan' 's Dispensatory, 1830.,} — 
"In this preparation the mercury is minutely divided, and 
possibly converted into the black oxide." 
Brande in 1833, gives rather a different version of the 
case : 
( Brande* s Manual of Pharmacy, 1S33J — "By tritura- 
ting mercury with chalk, a very small portion becomes con- 
verted into protoxide — the remainder is very minutely divi- 
ded; and thus, perhaps, acquires some activity as a mercurial 
when taken into the stomach." 
The same professor, in 1836, renders the subject a little 
more complex. 
(Brande's Manual of Chemistry, 1836. J — " Some have 
regarded these preparations as merely containing finely divi- 
ded mercury, and deny the possibility of oxidizing the metal, 
when pure, by mere agitation in the contact of atmospheric 
air, or trituration with viscid and oleaginous substances ; it is 
eertain that perfectly pure mercury, if at all thus acted on, is 
converted into an oxide extremely slowly, whilst mercury, 
containing a little lead or bismuth, is speedily converted into 
a black powder. 
" If heated or exposed to the sun's rays, the protoxide is 
converted into peroxide and metallic mercury." 
(Dr. Ure's Chemical Dictionary, 1835 J. — " By tritura- 
ting mercury with unctuous or viscid matters, it is changed 
partly into protoxide, and partly into very minute globules. 
By exposing mercurial ointment to a moderate heat, the 
globules fall down, while a proportion of the oxide remains 
combined with the grease." 
In the year 1837, Phillips revives the old theory with re- 
spect to pil. hydrarg. and unguentum hydrarg., and starts a 
