This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
I prefer the designation above given to that of Indian Hemp, ordina. rily applied to the medicine, because the latter name is habitually used in this country for the Apocynum cannabinum, which is totally different, both in its botanical relations and medicinal properties, from the substance now under consideration.
Hemp of India, considered as a medicine, consists of the dried flowering tops of Cannabis saliva, which is a native of the interior of Asia, but cultivated in many parts of the world, and to a considerable extern' in our own Western States. It is only, however, the product of the plant grown in the East Indies that is used medicinally. Its virtues reside mainly in a resinous exudation, which is thrown out in hot weather, upon the surface of the plant, rendering it clammy and adhesive to the fingers. This is produced much more largely in the Indian than in the European plant, probably owing simply to the difference of climate. The hemp of this country, if we are to judge from the odour it exhales when growing as a crop in the fields, and its viscidity to the touch, ought to be efficacious; and it would be an object worthy of attention to investigate this point experimentally.
In Hindostan the tops are cut after flowering, and when dried are tied together in bundles, two feet in length, each containing about twenty-four plants. These bundles are called ganjah or gunjah by the natives; and are essentially the same as the hashish of the Arabs. Bang is a name given to a mixture of the leaves and capsules, without the stem. The resinous exudation is collected in various methods from the growing plants in the flowering period, and formed into small masses which are called churrus. It is an alcoholic extract from the dried tops, or gunjah, that is recognized in the U. S. Pharmacopoeia, under the name of Extract of Hemp or Extractum Cannabis. In the British Pharmacopoeia the preparation is recognized by the name of Extractum Cannabis Indicae.
The tops of hemp, when fresh, have a characteristic odour, which, in the growing plant, is said sometimes to produce narcotic effects; and, in passing by fields of hemp, I have myself either felt, or imagined that I have felt, something of the kind. This odour is diminished in drying, and in the tops, as imported, is relatively very faint. Their taste is feeble and bitterish. The churrus, as described by Dr. Royle, is of a blackish-gray, blackish-green, or dirty olive colour, a fragrant and narcotic odour, and a slightly warm, bitter, and acrid taste. The best extract, as sold in our shops, is soft, of a blackish-green colour, a feeble narcotic odour, and a taste which is very slight at first, but becomes bitterish and herbaceous, and leaves a slight sense of acrimony for some time in the mouth.