By decomposition with sulphuric acid, narcotine yields Cotarnine, an undoubted base, together with Opianic Acid, and certain derivatives of the latter.
The discovery of another base, Codeine, was made in 1832 by Robiquet. It dissolves in 17 parts of boiling water, forming a highly alkaline solution which perfectly saturates acids, and exhibits in polarized light a levogyre power. Codeine is also readily soluble at ordinary temperatures in 7 parts amylic alcohol, and in 11 of benzol.
The codeine of commerce is in very large crystals containing 2 atoms = 5·66 per cent. of water. By crystallization from ether the alkaloid may be obtained in small anhydrous crystals.
Since 1832 other alkaloids have been found in opium, as may be seen in the following table, which includes all the 17 now known.[259]
A very large number of derivatives of several among them have been prepared, of which we point out a few in smaller type. The molecular constitution of these opium alkaloids being not yet thoroughly settled, we add only their empirical formulæ, which however exhibit unmistakeable connections.
Papaverosine discovered by Deschamps in poppy heads ([p. 42]) can hardly be absent from opium. In some points it appears to resemble cryptopine.
Among the peculiar non-basic constituents of opium, the first to call for notice is Meconic Acid, C₇H₄O₇, discovered, as already observed, by Sertürner in 1805. It is distinguished by the red colour which it produces with ferric salts, the same as that of ferric sulphocyanate; but the latter only dissolves in ether. Meconic acid is soluble in 4 parts of boiling water, but immediately gives off CO₂, and the remaining solution instead of depositing micaceous crystalline scales of meconic acid, yields on cooling (but best after boiling with hydrochloric acid) hard granular crystals of Comenic Acid, C₆H₄O₅.
Lactic Acid was discovered by T. and H. Smith in the opium-liquors produced in the manufacture of morphine. These chemists regarded it as a peculiar body, and under the name of Thebolactic Acid, exhibited it together with its copper and morphine salts at the London International Exhibition of 1862. Its identity with ordinary lactic acid was ascertained by Stenhouse (whose experiments have not been published) and also by J. Y. Buchanan.[260] T. and H. Smith consider it to be a regular constituent of Turkey opium; they obtained it as a calcium salt to the amount of about 2 per cent., and have prepared it in this form and in a pure state to the extent of over 100 lb. In our opinion it is not an original constituent of poppy-juice.
NATURAL ALKALOIDS OF OPIUM
and a few of their Artificial Derivatives.