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.
The only varieties which it is necessary to notice are, first, the Turkey opium, including the Smyrna and Constantinople, and, secondly, the Egyptian.
This comes in masses of irregular size and shape, from half a pound to two and a half pounds in weight, originally probably spherical, but usually flattened, or irregularly angular, in consequence of the pressure to which they are subjected, while yet soft, in the cases containing them. On their outer surface are the remains of the leaves in which they were originally enveloped; and adhering to it, in greater or less number, the light reddish-brown capsules of a species of Rumex, added, no doubt, with the object of absorbing moisture, and preventing the adhesion of the lumps. These are usually, as first imported, soft and tenacious in the interior, but hard upon the surface. When completely dried by time and exposure, they are brittle, and have a somewhat shining though uneven fracture.
a. Smyrna Opium. Of the two varieties of Turkey opium, the Smyrna is most largely imported. It is, indeed, almost the only variety kept in our retail shops. Besides the characters above mentioned, it has the peculiarity, when cut into, and then torn, of exhibiting numerous minute shining tears, very obvious under the microscope, which somewhat resemble small seeds, and are no doubt the concrete drops of juice formed on the capsules, upon exudation, after these have been incised. Along with the tears are numerous minute pieces of the outer covering of the capsule itself, scraped off with the juice. The best Smyrna opium consists of these ingredients exclusively; but inferior specimens are often sent into market, variously and in different degrees adulterated, and frequently so much so as to unfit them for use in the shops. The adulterating materials are an extract made from the leaves, grapes freed from their seeds and crushed, different gummy matters, liquorice, minute stones or pieces of metal, etc. Different samples of Smyrna opium vary in the quantity of morphia they contain from 3 to 13 per cent. The better kinds ought to yield at least 8 per cent. to a careful analysis. Good Smyrna opium is of a light reddish-brown colour in the interior. When blackish, of a weak empyreumatic odour, a sweetish taste, a viscid or greasy consistence an entirely dull fracture when dry, or containing obvious impurities, it should be regarded as inferior. If wholly without the Rumex capsules, or very scantily supplied with them, it may be looked on suspiciously, as probably of the kind which is said to be "made over again" in some of the Mediterranean ports.
b. Constantinople Opium. This, so far as it is a distinct variety, is characterized by the entire want of the tears which distinguish the genuine Smyrna opium. But the drug brought from Constantinople has probably been taken thither from all the different parts of the Turkish dominions where it is produced: and it is not, therefore, a matter of surprise that, under this name, Smyrna and Egyptian opium should have found their way into commerce.
This is in flat, roundish cakes, of different sizes, from half an ounce to a pound in weight, and often either wrapped in a poppy leaf, or presenting vestiges of the leaf, so applied that the midrib divides the cake into two equal parts. It has none of the Rumex capsules, and is always hard and brittle, breaking with a smooth fracture of a waxy lustre. It has usually much less morphia than good Smyrna opium, and should not be kept for use in the shops.
It is important that only good opium, of a strength at least approaching to uniformity, should be kept for internal use, or for making those preparations, the strength of which depends on that of the opium used; otherwise it would be impossible to have any fixed dose of this must important medicine, or to prescribe it with any certainty of obtaining its peculiar effects in the degree desired. The inferior kinds, should they be admitted into the country, ought to be employed exclusively by the manufacturers in the preparation of morphia or the other alkaloids.