52 Professor Burnett’s 
Herbarum, Plantaginis, Plantarum, Querctis, Tartari, and 
many others, as each vegetable was considered to afford a 
peculiar salt: while, in truth, none of them differ essentially 
from each other, the only variation being in their relative 
degrees of impurity; so that the terms Sal vegetabilis, or Sal 
plantarum yel herbarum, would conveniently include the 
whole. And yet, even now, or very lately, as I have been 
credibly informed, some persons will give a quadruple or quin- 
tuple price for Sal absinthii, an impure subcarbonate of pot- 
ash, obtained from wormwood, to what they will for the same, 
but more pure and valuable drug, derived from common and 
less costly sources. 
This is but a solitary example, yet it may serve to illustrate 
the whole. 
Shall I add a further illustration, oxalic acid, if procured 
alone from the plants whence sprang its name, (Oxalis aceto- 
sella, corniculata, &c.) would be a very expensive drug: even 
when at first, under the appellation Acidum sacchari, it was 
formed by the destruction of sugar, it was, within my recol- 
lection, sold in this town at 3s. 6d. and 4s. per ounce; but 
now it may be bought at the manufacturing chemists for 
about half that sum per pound. 
Probably a like fortune awaits many of the proximate prin- 
ciples, in modern times discovered, and still considered to be 
distinct. Thus, Colchicum is doubtless a useful medicine, 
though fashion has somewhat enhanced its fame, while 
Gratiola, the old Gratia Dei, and Veratrum album, or white 
hellebore, have completely fallen into disuse, if not into dis- 
repute; and yet the active principle is in all the same, and 
might, if extracted from either, be indifferently used, and 
with equal advantage and effect. May not this indicate the pro- 
priety of extracting veratria from hedge hyssop, or veratrum, 
where those plants abound, rather than from the expensive 
colchicum? ‘These instances must likewise indicate the ad- 
vantages likely to accrue from an intimate acquaintance with 
the proximate principles of vegetables, when we may find our 
active agents, not in one situation only, but recognize them 
in many, and seek them wherever they may be most abun- 
dantly present, or most easily be found. 
I fear that an accumulation of the evidence of how much 
is wanted to be known on the points which this Society 
has proposed as the objects of its chief inquiry, might 
weary the attention of the meeting. I will, therefore, add 
but one example more. ‘The value of Peruvian bark is 
by all acknowledged, and it is likewise known to every 
one that there are many species of Cinchona, differing in 
