In the year 1826, Dublanc[261] observed in opium a peculiar substance having neither basic nor acid properties which was afterwards (1832) prepared in a state of purity by Couerbe. It has been called Opianyl or (by Couerbe) Meconine. It has the composition C₁₀H₁₀O₄ = C₆H₂·CH₂·O·CO(OCH₃)₂. Meconin forms prisms which fuse under water at 77° C. or per se at 110°, and distil at 155°; it dissolves in about 20 parts of boiling water, from which it may be readily crystallized. Meconin may be formed by heating narcotine with nitric acid.

An analogous substance Meconoiosin C₈H₁₀O₂ = C₆H₂·(OH)₂·(CH₃)₂, has been discovered in 1878 by T. and H. Smith. Meconoiosin is readily soluble in 27 parts of cold water, and melts at 88° C. When heated with slightly diluted sulphuric acid, and when the evaporation has reached a certain point, meconoiosin produces a deep red; with meconin the coloration is a beautiful green.

Proportion of peculiar constituents—The substances described in the foregoing section exist in opium in very variable proportion; and as it is on their presence, but especially that of morphine, that the value of the drug depends, the importance of exact estimation is evident.

Opium whether required for analysis or for pharmaceutical preparations has to be taken exclusively in the dry state. The amount of water it contains is so uncertain that the drug must be reduced to a fixed standard by complete desiccation at 100° C., before any given weight is taken.

Morphine—Guibourt[262] who analysed a large number of samples of opium, and whose skill and care in such research are not disputed, obtained from a sample of French opium produced near Amiens, 22·88 per cent. of morphine crystallized from spirit of wine. This percentage has not to our knowledge been ever exceeded. From another specimen produced in the same district he got 21·23 per cent., from a third 20·67. The lowest percentage from a French opium was 14·96,—in each case reckoned on material previously dried.

Chevallier extracted from opium grown by Aubergier at Clermont in the centre of France, 17·50 per cent. of morphine. Decharmes from a French opium obtained 17·6 per cent., and Biltz from a German opium 20 per cent. Opium produced in Württemberg sent to the Vienna Exhibition of 1873 afforded Hesse 12 to 15 per cent. of morphine; and opium from Silesia 9 to 10 per cent.[263]

A pure American opium collected in the State of Vermont yielded Proctor 15·75 per cent. of morphine and 2 percent of narcotine.[264]

The opium of Asia Minor furnishes very nearly the same proportions of morphine as that of Europe. The maximum recorded by Guibourt is 21·46 per cent. obtained from a Smyrna opium sold in Paris. The mean yield of 8 samples of opium sent by Della Sudda of Constantinople to the Paris Exhibition of 1855 was 14·78 per cent. The mean percentage of morphine afforded by 12 other samples of Turkey opium obtained from various sources was 14·66.

Chevallier[265] states that Smyrna opium, of which several cases were received by Merck of Darmstadt in 1845, afforded 12 to 13 per cent. of pure morphine reckoned upon the drug in its fresh and moist state.

Fayk Bey[266] analysed 92 samples of opium of Asia Minor, and found that half the number yielded more than 10 per cent. of morphine. The richest afforded 17·2 per cent.

From the foregoing statements we are warranted in assuming that good Smyrna opium deprived of water ought to afford 12 to 15 per cent. of morphine, and that if the percentage is less than 10, adulteration may be suspected.

Egyptian opium has usually been found very much weaker in morphine than that of Asia Minor. A sample sent to the Paris Exhibition of 1865 and presented to one of us by Figari Bey of Cairo, afforded us 5·8 per cent. of morphine and 8·7 of narcotine.

Persian opium appears extremely variable, probably in consequence of the practice of combining it with sugar and other substances. It is however sometimes very good. Séput[267] obtained from four samples the respective percentages of 13·47, 11·52, 10·12, 10·08 of morphine, the opium being free from water. Mr. Howard as already stated (p. 49) extracted from Persian opium, not previously dried, from 8 to 10·75 per cent. of morphine.

East Indian opium is remarkable for its low percentage of morphine, a circumstance which we think is attributable in part to climate and in part to a method of collection radically defective. It is scarcely conceivable that the long period during which the juice remains in a wet state,—always three to four weeks,—does not exercise a destructive action on its constituents.

According to Eatwell[268] the percentage of morphine in the samples of Benares opium officially submitted for analysis gave the following averages.—

The same observer has recorded the results of the examination of freshly collected poppy-juice, which in three instances afforded respectively 1·4, 3·06, and 2·89 per cent. of morphine, reckoned on the material deprived of water; but the conditions under which the experiments were made appear open to great objection.[269]

Such very low results are not always obtained from East Indian opium. In a sample from Khandesh furnished by the Indian Museum, we found 6·07 of morphine. Solly from the same kind obtained about 7 per cent.

Patna Garden Opium which is the sort prepared exclusively for medicinal use, afforded us 8·6 per cent. of purified morphine and 4 per cent. of narcotine.[270] Guibourt obtained from such an opium 7·72 per cent. Christison from a sample sent to Duncan of Edinburgh in 1830,[271] 9·50 per cent. of hydrochlorate of morphine.

Samples from the Indian Museum placed at our disposal by Dr. J. Forbes Watson gave[272] us the following percentages of morphine:—Medical (Indian) Opium, 1852-53, portion of a square brick, 4·3; Garden Behar Opium, 4·6; Abkāri Provision Opium, Patna, No. 5380, 3·5; Sind Opium, No. 28, 3·8; Opium, Hyderabad, Sind, 3·2 (and 5·4 of narcotine); Malwa Opium, 6·1.

With regard to the percentage of morphine in Chinese Opium, the following data have been obligingly furnished to us by Mr. T. W. Sheppard, F.C.S., Opium Examiner to the Benares Opium Agency, of analyses made by himself from samples of the drug procured in China by Sir R. Alcock:—Szechuen opium, 2·2; Kweichow, 2·5; Yunnan, 4·1; Kansu, 5·1 per cent. Mr. S. informs us that Dr. Eatwell obtained in 1852 from Szechuen opium 3·3, and from Kweichow opium 6·1[273] per cent.—the opium in all instances being reckoned as dry. The samples examined by Mr. S. contained 86 to 95 per cent. of dry opium, and yielded (undried) 36 to 53 per cent. of extract soluble in cold water. The proportion of morphine in the sample of Chinese opium analysed by Dr. Jamieson (p. 55) was nearly 7·2 per cent. calculated on the dry drug.

Pseudomorphine—occurs only in very small quantities. Hesse found it in some sorts of opium to the extent of 0·02 per cent.—in others still less.

Codeine—has been found in Smyrna, French and Indian opium, but only to the extent of ⅕ to ⅖ per cent. T. and H. Smith give the proportion in Turkey opium as 0·3 per cent.[274]

Thebaine—which has likewise been obtained from French opium, amounts in Turkey opium according to Merck to about 1 per cent. In the latter sort T. and H. Smith found only about 8·15 per cent., but of

Papaverine—in the same drug, 1 per cent.

Narcotine—exists in opium in widely different proportions and often in considerable abundance. Thus Schindler obtained in 1834 from a Smyrna opium yielding 10·30 per cent. of morphine, 1·30 per cent. of narcotine. Biltz (1831) analysed an oriental opium which afforded 9·25 per cent. of morphine and 7·50 of narcotine. Reveil (1860) obtained from Persian opium not rich in morphine, from half as much to twice as much narcotine as morphine. The utmost of narcotine was 9·90 per cent. We have found in German opium of undubitable purity[275] 10·9 per cent. of narcotine.

East Indian opium was found by Eatwell (1850) always to afford more narcotine than morphine,—frequently twice as much. The sample from Khandesh referred to on the opposite page, afforded us 7·7 per cent. of pure narcotine.

French opium collected from the Pavot œillette sometimes affords neither narcotine, thebaine, nor narceine.[276]

Narceine—Of this substance Couerbe found in opium 0·1 per cent.; T. and H. Smith 0·02 and Schindler 0·71.

Cryptopine—exists in opium in very small proportion. T. and H. Smith state that since the alkaloid first came under their notice, they have collected of it altogether about 5 ounces in the form of hydrochlorate, and this small quantity in operating on many thousands of pounds of opium. But they by no means assert that the whole of the cryptopine was obtained.

Rhœadine—is also found only in exceedingly minute quantity.

Meconic Acid—If the average amount of morphine in opium be estimated at 15 per cent., and the alkaloid be supposed to exist as a tribasic meconate, it would require for saturation 3·4 per cent. of meconic acid. Wittstein obtained rather more than 3 per cent., T. and H. Smith 4 per cent., and Decharmes 4·33. Opium produced in Vermont yielded, according to Proctor (1870) 5·25 per cent. of meconic acid. The quantity of acid required to unite with the other bases assuming them to exist as salts can be but extremely small.

Estimation of Morphine in Opium—The practical valuation of opium turns in the first instance upon the estimation of the water present in the drug, and in the second upon the proportion which the latter contains of morphine.[277]

The first question is determined by exposing a known quantity of the drug divided into small slices or fragments to the heat of a water-bath until it cease to lose weight.

For the estimation of the morphine many processes have been devised, but none is perfectly satisfactory.[278] That which we recommend is thus performed:—Take of opium previously dried at 100° C., as above stated, and powdered, 10 grammes; shake it with 100 grammes alcohol 0·950 sp. gr., and filter after a day or two. The weight of the liquid should be made equal to 100 grammes. Add to it 50 grammes of ether and 2 grammes of ammonia water 0·960 sp. gr.; collect the crystals of opium which separate slowly, after a day or two, dry them at 100° C., and weigh them.—On applying this method to Indian opium, we were but little satisfied with it.

Commerce—By official statistics it appears that the quantity of opium imported into the United Kingdom in 1872 was 356,211 lb., valued at £361,503. The imports from Asiatic and European Turkey are stated in the same tables thus:—

It is thus evident that the drug used in Great Britain is chiefly Turkish. The import of opium from Persia has been very irregular. In 1871, 21,894 lb. are reported as received from that country; in 1872, none.

Except that a little Malwa opium has occasionally been imported, it may be asserted the opium of India is entirely unknown in the English market, and that none of it is to be found even in London in the warehouse of any druggist.

As to other countries, we may point out that in 1876 the import of opium (prepared) into the colony of Victoria was valued at £104,557.

Uses—Opium possesses sedative powers which are universally known. In the words of Pereira, it is the most important and valuable medicine of the whole Materia Medica; and we may add, the source by its judicious employment of more happiness and by its abuse of more misery[279] than any other drug employed by mankind.

Adulteration—The manifold falsifications of opium have been already noticed, and the method by which its more important alkaloid may be estimated has been pointed out. Moreover as already stated, neither tannic acid nor starch ever occur in genuine opium; and the proportion of ash left upon the incineration of a good opium does not exceed 4 to 8 per cent. of the dried drug. Another criterion is afforded by the amount soluble in cold water which ought to exceed 55 per cent. reckoned on dry opium. Finally, if we are correct, the gum contained in pure opium is distinct from gum arabic, being precipitable by neutral acetate of lead. If we exhaust with water opium falsified with gum arabic, the mucilage peculiar to opium will be precipitated by neutral acetate of lead, the liquid separated from the precipitate will still contain the gum arabic which may be thrown down by alcohol. If gum is present to some extent, an abundant precipitate is produced.