August 19,1871.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
115 
traced to the presence of a minute quantity of air (about 
^i_th part) in the carbonic acid. On augmenting the 
pressure after liquefaction, the volume slowly diminished, 
but at a much faster rate than in the case of ordinary 
liquids. Later experiments carried to much higher 
pressures have fully confirmed this result. At 21°-5 
similar results were obtained, but a pressure of nearly 
60 atmospheres was required before liquefaction began. 
At 30°’9 C., or 87°*7 Fahr., the critical point of tem¬ 
perature is reached. It is the temperature at which 
liquid ceases to be formed under any pressure. At a 
temperature a little below this point the surface of sepa¬ 
ration between liquid and gas becomes very faint and 
loses its curvature, the density and other physical pro¬ 
perties of the liquid and gas being now identical and the 
tube filled with homogeneous matter. If the tempera¬ 
ture and pressure be kept steady, no evidence of hetero¬ 
geneity will be obtained by optical tests under the most 
varied conditions of volume. 
If we now follow the course of a given volume of car¬ 
bonic acid gas at 31°-1, or 0°-2 above the critical point, 
we shall find that its course resembles that of the gas at 
lower temperatures till the volume is reached at which 
liquefaction might be expected to begin. A rapid but 
not (as in the case of the formation of liquid) abrupt fall 
then supervenes, after which the carbonic acid undergoes 
a slow diminution of volume as the pressure augments. 
The curves, which arc here exhibited as they were re¬ 
presented in the Bakerian lecture, illustrate very clearly 
these statements. We have thus carbonic acid at 0 o, 2 
above the critical point, and at a pressure of 73 atmo¬ 
spheres behaving very nearly as if it liquefied. At this 
pressure an augmentation of only -gVth of the entire 
pressure diminishes the volume of the carbonic acid to 
about one-half. Yet during the whole of this fall, no 
evidence of heterogeneity, or of two states of matter 
present together in the tube, could at any period be ob¬ 
tained. Carbonic acid at this temperature of 31°’l, and 
under a pressure of 75 atmospheres, behaves much more 
as a liquid than as a gas when the pressure is either 
augmented or diminished; yet it never exhibits under 
any conditions the characteristic properties of the liquid 
state; that is to say, no surface of separation is formed 
by change of pressure, nor will it collect into drops and 
form a cloud. 
(To be continued.) 
least I can recommend it to my fellow-pharmacists as a 
profitable enterprise. 
This being the second season only for the new busi¬ 
ness, it is impossible to present any very full or complete 
details as to the success and profits attending the growth 
of the various medicinal articles, for, besides the time 
being too short, the seasons have both been very un¬ 
favourable. We have had such excessive rains that the 
ground has been almost saturated with water during a 
great part of the growing period; still I hope that the 
few results I am able to communicate will not prove 
uninteresting. 
The first and one of the greatest difficulties was the 
procuring of suitable seeds, fresh and good; there is so 
little demand for such that they are sometimes old and 
almost worthless before they come into the purchaser’s 
hands, so that very few of them will germinate. Some 
of the needed articles were found among the seed dealers 
of New York and Boston, others were obtained from the 
establishment of Yilmorin, Paris, France. 
ATROPA BELLADONNA. 
Two ounces of seed was planted, late in May, in drills 
of 2b feet apart, and covering 1-lGth of an acre of ground, 
with the intention of transplanting it into rows, at suit¬ 
able distances, the following season. The plants came 
up moderately thick, and attained a fair growth before 
the close of the summer; in one or two instances flowers 
appeared on them late in September. The outer leaves 
were partially stripped before severe frost came, carefully 
leaving the crowns uninjured. The product yielded 11 
lb., when dry. Thinking that the plants were sufficiently 
vigorous and well established to withstand the cold of 
winter, they were not in any -way protected. The sea¬ 
son proved too severe for them, the following spring- 
showing every plant dead, with its roots quite rotten. 
From the herb gathered in the fall some preparations 
were made—fluid extract and solid extracts, watery and 
alcoholic. On comparison with similar preparations from 
like quantities, and made with equal care from a fair 
sample of the imported herb, the following results were 
noted:— 
1 lb. of herb of Canadian 
growth yielded of solid 
aqueous extract, 2 oz. 7 drs. 
23 grs. 
Solid alcoholic extract, 1 
oz. 5 drs. 25 grs. 
1 lb. of imported herb 
yielded of solid aqueous ex¬ 
tract, 3 oz. 5 drs. 10 grs. 
Solid alcoholic extract, 2 
oz. 2 drs. 30 grs. 
SOME MEDICINAL PLANTS OF CANADIAN 
GROWTH. 
BY W. SAUNDERS, LONDON, ONTARIO. 
Having become somewhat debilitated by close applica¬ 
tion to business, I purchased two years since a farm with 
the intention of planting it with fruits of various sorts, 
and growing as well such varieties of foreign and indi¬ 
genous medicinal plants as should be found suitable to 
the soil and climate. The personal supervision requisite 
to begin and carry out successfully an undertaking of 
this sort would, I knew, oblige me to be away much from 
the shop, and exchange its closer atmosphere and seden¬ 
tary occupations for the more active employments and 
purer air of the country. I believe, as a class, we phar¬ 
maceutists are fond of our profession, and there are 
charms as well as ties about it which seem to draw one 
naturally into long hours of steady application. It 
requires a considerable effort to break away from these 
influences, and unless one is obliged to do so, good reso¬ 
lutions are often set aside to suit occasion and conveni¬ 
ence. My undertaking may not, at present, be regarded 
as a paying one; but there will surely be a large sum to 
place to the credit side on account of improved health 
and increasing vigour,—more than sufficient, I think, to 
balance any losses which may arise; and in this way at 
Showing a difference of yield in favour of the imported 
herb of 5 drachms 47 grains aqueous extract, and 5 
drachms and 5 grains alcoholic extract. 
The fluid extract made from the herb of Canadian 
growth has the narcotic odour of the plant in a higher 
degree than that from the imported herb; the odour is 
so strong in the former case that it approaches pungency. 
It has been used in a few cases in practice, and as far as 
I have been able to ascertain, has acted fully as well as 
that made from the foreign plant. 
The solid aqueous extracts closely resemble each other 
in odour, although I am inclined to regard that from the 
Canadian plant as strongest. 
The alcoholic extracts differ in odour very materially ; 
that from the herb of Canadian growth is much heavier 
and more powerful than the other. I have had no op- 
portunity of having these latter articles tested in medical 
practice. 
I1Y0SCYAMUS NIGER. 
One ounce of seed in this instance was planted at tno 
same time and in the same manner as that of the bella¬ 
donna, occupying a space of less than l-20th of an acre. 
The plants came up thin, a large proportion of the seeds 
failing to germinate. Ten pounds of leaves were ga¬ 
thered about the 1st of October. Some of the plants 
belonged to the annual variety, others to the biennial; 
most of the latter, in this instance, stood the winter well 
