According to this view hyoscyamine ought to be the hyoscinate of
hyoscine, or at any rate an isomer of this body. It is to be remarked
that they compare hyoscinic acid not with tropic acid, of which it
possesses the composition, but with atropic acid, C_{9}H_{8}O_{2}. I
have worked with the hyoscyamine of both Merck and Trommsdorff, as well
as with a product which I obtained from hyoscyamus seeds myself. The
best way of purifying the alkaloid is by recrystallizing its gold salt
several times, so as to obtain it in brilliant yellow plates, melting
at 320° F. By passing a stream of hydrosulphuric acid gas through the
liquor the gold is precipitated in the form of sulphide. The liquid is
filtered and evaporated, precipitated by an excess of a strong solution
of potassium carbonate, and the alkaloid extracted by chloroform.
The solution is dried over carbonate of potassium, and part of the
chloroform is distilled off. By leaving the solution to evaporate
spontaneously the alkaloid is obtained in silky crystals. The crystals
are then dissolved in alcohol, which, on being poured into water, parts
with them in the same form.
Hyoscyamine crystallizes in the acicular form, with greater difficulty
even than atropine, it also forms less compact crystals. Its fusing
point is 149.6° F. I have not yet succeeded in crystallizing any of
its more simple salts. The double platinum salt melts at 392° F., with
decomposition. The double gold salt, which has been described above,
does not melt in boiling water, and its aqueous solution is reduced
neither by boiling nor by long exposure to light. By leaving the hot
saturated solution to cool it does not cloud, but the double salt
separates pretty rapidly in the form of plates.
One liter of water containing 10 cubic centimeters of hydrochloric acid
at 1.19° dissolves 65 centigrammes of the salt at 146° F.
These characteristics allow us to differentiate atropine and
hyoscyamine, the reactions of which are almost identical, as will be
seen from the following table, which shows the action of weak solutions
of the acids named on the hydrochlorates of the bases:
_Reagents_. _Hyoscyamine_. _Atropine_.
Picric acid. An oil solidifying Crystalline precipitate.
immediately into
tabular crystals.
Mercuropotassic White cheesy Same.
iodide. precipitate.
Iodized potassic An immediate A brown oil crystallizing
iodide. precipitate of after a time.
periodate.
Mercuric chloride. Same as picric acid. Same.
Tannic acid. Slight cloud. Cloud hardly visible.
Platinum chloride. O. O.
_(To be continued.)_
* * * * *