September 7, 1872.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
181 
THE MICROSCOPE IN PHARMACY. 
BY HENRY rOCKLINGTON. 
(Continued from page 161.) 
Sassafras Radix. — Medulla .—When present, the 
medulla is composed of irregular sub-globose cells, 
unpitted, containing small quantities of starch and 
usually also a dark red-brown colouring matter. 
Wood Zone .—The wood is very light and porous, 
and is composed of pleurenchymatous cells, of vascular 
vessels, and the parench} r matous cells of the medul¬ 
lary ray. Viewed in cross section, the vessels are 
oval or circular, and in duplicate usually; the wood 
cells are irregularly shaped polyhedrons, the medul¬ 
lary rays composed of sub-cylindrical cells. 
Wood Cells .—These when viewed longitudinally 
are seen to be of the true pleurenchymatous type, 
are long with pointed ends, and are intimately co¬ 
herent. The vascular vessels are very large and 
clearly discernible by the unaided eye if a thin sec¬ 
tion be held up to the light. They are distinctly 
pitted, and have but moderately thick walls, which 
are very rarely completely perforate. The size, 
shape and arrangement of the pits are very varied. 
The larger vessels are somewhat minutely pitted, the 
pits being arranged with great regularity in close 
proximity with each other; are oval, their long axis 
being transversal to that of the vessel. These 
vessels form a very pretty object. Other vessels are 
coarsely pitted, the pits being “bars” rather than 
pits. The gradations between those extremes are 
gradual. The vessels are not reticulate, but certain 
of them manifest a disposition to tear longitudinally, 
as though they were formed by the adhesion of con¬ 
tiguous pitted wood cells. 
The cohesion of the vessels in linear series is 
usually oblique, the septa is usually partially ab¬ 
sorbed, a hernoid annulus remaining. When the 
septum has not been absorbed, it is pitted like the 
vessel. 
The cells of the medullary rays are sub-cylin¬ 
drical, and contain small quantities of starch and 
colouring matter. The starch is somewhat difficult 
of examination. The granules are rather small, 
ovate, and intensely doubly refractive. 
A well-executed longitudinal section mounted in 
Canada balsam, after a prolonged soaking, forms a 
very beautiful polariscope object when viewed with 
a neutral violet, a cyanogen blue, or a purple sele¬ 
nite. When the selenite, polarizing, and analysing 
prisms are properly adjusted, the variety of colours 
seen will surprise any one but a very blase polari- 
scopist. 
Cortical layers .—The presence of great quantities 
of colouring matter and other cell contents renders 
the examination of the cortical layers somewhat 
difficult. The sections must be carefully boiled, and 1 
then allowed to macerate, in alcohol before examina¬ 
tion, if a close examination be desired. The paren¬ 
chymatous cells of these layers do not present spe¬ 
cial features of interest. In shape they are irregu¬ 
larly modified sub-cylindrical cells; their walls are 
thin and unpitted. 
Medullary rays are present in the innermost 
layers. The outer cells, the sub-epiblema are cubic, 
uncompressed cells with rigid walls and stained a 
dark brown, almost black. The flat cells of the ex¬ 
terior have no special features. The liber cells of 
the bark are cord-like, very long, and very tough. A 
Third Series, No. 115. 
cross section of them is not easy of accomplishment; 
they are then seen to be tubes almost wholly filled 
with sclerogenous deposits. 
Canada balsam or dammar is the best medium in 
which to mount transverse sections. Longitudinal 
sections should be mounted in dammar and in gly¬ 
cerine. Before mounting them in balsam, they must 
be dried very gradually and carefully from the water 
in which they were immersed after being cut, and 
soaked in turpentine for some days. 
THE RELATION BETWEEN THE ODOUR 
OF GASES AND THEIR POWER OF RE¬ 
SISTING LIQUEFACTION. 
BY F. TREVES. 
With regard to this singular and marked relation, 
it is, in the first place, to be noted that those gases 
alone have odour that can be reduced to liquids or 
solids by the application of pressure or great cold. 
And reviewing this relation in another aspect, it will 
be found also that every gas that is inodorous is 
likewise quite irreducible by either cold or pressure. 
In the second place, the intensity or strength of the 
odour of any gas bears a marked relation to the 
power required to reduce that gas to a liquid or a 
solid state, the strength of the odour being always 
in inverse ratio to the amount of force requisite for 
condensation. These relations—to which attention 
is now for the first time called—I have found to 
exist (with very few exceptions) in the case of all 
kn own gases. Of the four elementary gases—* 
omitting fluorine—three, viz., oxygen, hydrogen and 
nitrogen, are quite inodorous, and at the same time, 
quite irreducible by either pressure or cold. "Whilst 
the fourth gas, chlorine, which is possessed of a most 
suffocating smell, is easily condensed to a liquid. 
To take the case of some of the more common com¬ 
pound gases, it will be noticed that carbonous oxide, 
which is inodorous, is also incondensible, whilst 
carbonic oxide, which has a faint, pleasant and 
pungent odour, can be brought not only to a liquid, 
but also to a solid state. Nitrous oxide again, which 
possesses a very faint yet decided smell, can bo 
liquefied and also solidified, but nitric oxide, which 
is an odourless gas, has never yet been reduced by 
any known means. Methyl hydride is not possessed 
of smell, and is not to be liquefied, whilst ethylene, 
with its faint garlic odour, liquefies at a temperature 
of 110° if under pressure. Acetylene, on the other 
hand, forms one marked exception to this general 
rule : it has a most distinct and far from pleasant 
smell and has as yet proved incondensible. In 
noticing, secondly, the ratio between the strength of 
the odour and the power required to reduce the gas, 
it will be seen that sulphurous acid, which possesses a 
smell more intense, perhaps, than that of any other 
known gas, being quite irrespirable, requires only a 
pressure of two atmospheres at 15°, or a tempera¬ 
ture of 17-8°, to reduce it to a liquid, whilst, on the 
other hand, no less than fifty atmospheres at a tem¬ 
perature of 7-2° are required to reduce nitrous oxide, 
a gas almost inodorous, to a liquid condition. 
Again chlorine is easily liquefied under about five 
atmospheres, whilst hydrochloric acid, the odour of 
which is very much less intense than that of chlorine 
itself, requires the application of at least forty atmo¬ 
spheres for proper reduction. Ammonia and sulphu- 
