PHARMACEUTICAL NOTICES. 
Ill 
with an excess of diluted nitric acid, which removes all the 
magnesia and leaves the oxide in a pure state. This is to be 
again well washed and dried between sheets of bibulous paper, 
but without compression or exposure to light or heat. It is 
pulverulent, inodorous and of a brown colour. Light acts on 
it very rapidly, and it must therefore be always kept in opaque 
bottles. 
Action of Charcoal on some of the Bitter Extracts. The 
employment of charcoal as a decolourizing agent is so fre- 
quently resorted to, that it is a matter of some consequence to 
ascertain whether in some cases, in removing the colouring 
principle, it does not at the same time act on other constitu- 
ents. It was several years since asserted by Duburga, that 
if the tincture of gentian be treated with charcoal, that it lost 
all its bitterness, whilst the tincture of centuary was not acted 
upon by this substance. In consequence of this statement, 
Dr. Hopff made a series of comparative trials on a number of 
vegetable extracts, and found that whilst some remained unaf- 
fected, others were deprived of almost all their previous bitter- 
ness; this was particularly the case with chamomile, sima- 
rouba, Iceland moss, &c. 
Nux vomica and false angustura were not affected by the use 
of small portions of animal charcoal ; but if an excess be em- 
ployed, and the digestion continued for some time, they lost 
almost all bitterness. This subject still presents a wide field 
for experimental inquiry, especially as regards the effect of 
this agent on the peculiar principles of vegetables, and more 
particularly on such as are remarkable for their bitterness, as 
quinia, &c. Dr. Hopff does not mention whether the extract 
of nux vomica, thus deprived of one of its most sensible quali- 
ties, still retained its other qualities unimpaired. Might not 
the strychnia, in thus losing its bitterness, also lose its poison- 
ous properties. 
Medicated Waters. — Most of the aromatic medicated wa- 
ters of the United States Pharmacopoeia are ordered to be 
