( 49 )
who, experimenting with the European plant, were able to throw no light on
the nature or amount of the active principle of the plant. Tscheppe's account,
which is the one best known, does not so much as mention any resinous extract.
For the next eighteen years one finds no reference of any importance either to
the plant or the drug. But in 1839, when O ' SHAUGIINESSY 1 first issued his
classical account of the plant and its effects, which two years later was incor-
porated in the official Bengal Dispensatory, the subject was taken up and fairly
thoroughly worked out by a number of investigators.
O'Shaughnessy himself made an estimate of the amount of extract that fresh
gánjá yields to alcohol, of which he says that he obtained 20 per cent. It has
been for some reason the experience of subsequent investigators that this
estimate of O'Shaughnessy's is too high. As has been shown in a former
chapter, this is not the case ; doubtless the lower results obtained by other
chemists have been owing to their treating the substance differently ; one of the
chief defects in those accounts of the plant in which the amount of extract
obtained has been used as a means of estimating the strength of the sample
examined, is the omission of any details of the treatment to which the sample
was subjected prior to its being treated with alcohol.
O'Shaughnessy's account was rapidly followed by the accounts of
n
SINGER2 and BoHLIG, 3 Who examined the leaves of European hemp. The most
noteworthy results of their analyses were the detection of 5 per cent. of green
resinous extractive by Schlesinger, and the observation by Bohlig that an oil, of
which he was able to obtain from the fresh plant about 1/3 per cent., had physio-
logical properties. In 1844 KANE . 1 r e - e x a m i n e d t h e p l a n t v e r y e x h a u s t i v e l y
without adding anything material to our knowledge.
In 1846 the resin of hemp was isolated by Messrs. T. and HS M I T H ,
a f i r m
of chemists in Edinburgh, in the following manner: Powdered gán já was
treated repeatedly under pressure with warm water till the washing
ceased to
be coloured. It was then left for two or three days to digest at moderate
temperature in a solution of bicarbonate of soda, in the proportion of one part
of the salt to two parts of the dried plant. Brown colouring matter, chlorophyll
and a peculiar oil were thus for the most part removed. The residue was now
carefully dried and digested in rectified spirit, the resulting tincture being;
treated with lime-water in the proportion of an ounce of fresh quick-lime to each
pound of gánjá. This removed all fatty matter and the remaining green colour-
ing matter. After filtering, the lime in solution was precipitated by means of
sulphuric acid and removed ; the solution being still slightly coloured was
rendered clear by animal charcoal. After filtration the greater part of the
alcohol was distilled off ; the remaining solution was then mixed with twice
its measure of water, and the rest of the alcohol allowed to evaporate, the resin
meanwhile sinking to the bottom of the vessel. The fluid portion being run
off, the resin was treated with cold water and then dried in thin layers. This
resin was termed by the Messrs. Smith cannabin. This resin is a brown amor-
phous solid, burning with a bright flame and leaving no ash. It has a powerful
intoxicant effect.
From this time till 1857 nothing material was added to the chemical history
of the plant though in 1851 A. CHRISTISON 6 and in 1856 G. MARTIUS7 wrote
important papers on the general history and use of the hemp plant, the latter
s e p a r a t i n g t h e r e s i n f r o m t h e o r d i n a r y a l c o h o l i c e x t r a c t . I n 1 8 5 7 P E R S O N N E
8
repeated
separating
distillation performed by Bohlig seventeen years before, and found
that when water is repeatedly distilled from fresh hemp in large quantities, new
hemp being used for each_ distillation, ammonia passes over and with it a volatile
oil lighter than water. This oil is amber-coloured, has the hemp-smell, some-
times deposits in part as a crystalline substance, and may be separated with ease
into two bodies cannabene, liquid and colourless, with the chemical formula
C18 H20, the other a solid, separating in platy crystals from alcohol, hydride of
¹ On the preparations of the Indian Hemp or Gánjá, their effects on the animal system ; Calcutta (1839).
² Pharm
aceut. Centralblatt. (1840), p. 490.
³ Pharmaceut. Centralblatt. (1840), p. 519.
4. Philosoph. Magazine, February 1814.
5 Pharmaceut. Journal, vi (1817), p. 171.
6 Edinbu
rgh Monthly Journal of Medical Science, July 1851, On the nature, history, action and uses
of Indian Hemp.
7 Studien ueber den Hanf, Lei pzi g, 1856.
8 Journal de Pharmacie, vol. 39 (1837), 48