This is the only other opiate alkaloid, the effects of which, until very recently, have been investigated. For the method of procuring it, the reader is referred to the Dispensatories. It is white, crystallizable in octohedra, much more soluble in water than the other alkaloids mentioned, soluble also in alcohol and ether, but insoluble in alkaline solutions. It is distinguished from morphia by the difference of its solubilities, and by not becoming blood-red with nitric acid, or blue with sesquichloride of iron. It is contained in small proportion in opium, constituting almost always less than 1 per cent. Various accounts of its effects on the system have been given, among the most reliable of which is that of Dr. Gregory, of Edinburgh. From three grains of it he obtained no obvious effect: but when the dose was augmented to five or six grains, he found it to increase the frequency of the pulse, to produce a feeling of warmth in the head and face, and itching in the skin, and to exhilarate the spirits. This condition, after lasting for several hours, was followed by unpleasant depression, with nausea and sometimes vomiting. This is so exactly the operation of morphia, in doses insufficient to produce sleep, as to suggest the inference that the codeia employed contained a small proportion of the stronger alkaloid; and, from the statement of Pereira, that all the specimens he had tried of codeia produced an orange-yellow colour with nitric acid (Mat. Med., 3d ed., p. 2099), it is highly probable that this impurity is very commonly present. M. Barbier, of Amiens, found codeia, in the dose of a grain or two, to relieve painful affections of the viscera supplied with nervous influence from the sympathetic, while it produced no effect in pains of the back or extremities. Hence, he conceived it to act especially on the sympathetic system of nerves. It did not disturb the circulation or digestion, or produce constipation; and, when taken largely enough to cause sleep, occasioned no signs of cerebral congestion. Dr. Miranda, of Havana, found it decidedly beneficial in dyspepsia. It has not, however, been as yet proved to possess powers which are likely to render it a valuable article of the Materia Medica. Mauthner recommends it in the non-inflammatory spasms of the orbicular muscle of the eyelids occurring in infants. He applies a solution of one part in four of almond oil, by means of a hair pencil, three times daily to the lids. More recently, Professor Aran, of Paris, has made extensive use of codeia, and says of it that it possesses the most valuable properties of opium, is inferior to morphia in the relief of pain only because it requires to be given in larger doses, and is superior to it in these respects, that it does not cause heavy and agitated sleep, does not induce perspiration or cutaneous eruptions, nor trouble digestion, and finally, that it does not cause nausea, vomiting, or obstinate constipation. It is specially valuable in procuring calm, relieving obstinate cough, and suppressing the pains of rheumatism, gout, and cancerous affections. (Am. Journ. of Med. Sci., Jan. 1863, p. 184).

The French Codex prepares a syrup of codeia by dissolving twenty centigrammes of the powdered alkaloid in thirty-four grammes of distilled water, and adding sixty-six grammes of pure sugar. A tablespoonful of the syrup contains only four centigrammes, or somewhat more than half a grain of codeia.

In relation to the other peculiar principles of opium, paramorphia or the baina was found by Magendie to produce tetanic spasms in the quantity of a grain, when thrown into the jugular vein of one of the lower animals, and thus to resemble strychnia and brucia in its action; opi-ania, according to Dr. Hinterberger, exercises powerful narcotic effects on the lower animals; and narcein or narceia has been thrown into the jugular vein of a dog, in the quantity of two grains, in several instances, without any observable effect. Not much is known of the operation of meconin or meconic acid; but they are supposed to have little effect.*

* Such was the extent of our knowledge on the subject of the active principles of opium, at the period of publication of the second edition of this work; and I have allowed the statements in the text to remain with little alteration, because, though most important investigations have been subsequently made, throwing much new light on the subject, yet the results have not assumed so definite a form, nor been so far confirmed by trial on the human subject, as to justify their admission among the established facts of our science. I have, therefore, deemed it best to introduce a notice of these researches in the form of a note, to await the result of future inquiry.

The author of the experiments referred to was M CI. Bernard, of Paris. They were performed on several different species of the lower animals, and great care was taken to avoid sources of error; so that the conclusions may be received with great confidence; though it must be remembered that they cannot be relied on implicitly in relation to man. They relate to the relative powers of the several peculiar principles which have been extracted from opium; and these powers were tested by injecting solutions of the alkaloids into the subcutaneous areolar tissue: the effects upon the same animals being noted and compared, and the comparison afterwards extended to the different species, in all of which the results obtained were remarkably uniform.

M. Bernard tried six of these principles; morphia, narceia (narcein), codeia, nar-cotina, papaverina, and thebaina (thebain). Of these, the first three alone, namely. morphia, narceia, and codeia, were found to possess soporific properties; and these, still retains it in considerable quantities after maceration in water. The portion which water dissolves is probably taken up through the agency of the free acid of the opium. Narcotina is in white, silky, flexible, acicular crystals, without, smell or taste, insoluble in cold water and alkaline solutions, very slightly soluble in boiling water, slightly so in cold and much more freely in hot alcohol, and readily soluble in ether and the diluted acids. The volatile and fixed oils also dissolve it. Though capable of uniting with the acids to form definite compounds, and with the muriatic and sulphuric acids to form crystallizable salts. it does not affect the colour of litmus, and must be considered as possessing but feeble alkaline powers. It is distinguished from morphia by its solubility in ether, by assuming a yellowish instead of red colour with nitric acid, and by the want of the other properties before mentioned as characteristic of that alkaloid. If it be mixed with sulphuric acid, and then a piece of nitre be added, it becomes deep-red, while morphia, under similar circumstances, becomes brownish or olive-green. In this case, it is a mixture of the nitric and sulphuric acids that acts. Though tasteless, when pure, the compounds which it forms with the acids are very bitter.