Ammoniacum is obtained from the mature plant, the ripe mericarps of which, ⅜ of an inch in length, are often found sticking to the tears. By pressure the tears agglutinate into a compact mass, which is the Lump Ammoniacum of the druggists. It is generally less pure than the detached grains, and fetches a lower price.
Chemical Composition—Ammoniacum is a mixture of volatile oil with resin and gum. We obtained only ⅓ per cent. of oil which we find to be dextrogyrate; we failed in obtaining terpin (see Galbanum, [p. 322]) from it. The oil has the precise odour of the drug, contains, according to our experiments, no sulphur; a similar observation was made by Przeciszewski[1238]. Vigier[1239] asserts that it blackens silver, and that after oxidation with nitric acid, he detected in it sulphuric acid. He states that, with hydrochloric acid, the oil acquires a fine violet tint passing by all shades to black; we failed in obtaining this coloration. By diluting the oil with bisulphide of carbon, and then adding mineral acids, we observed only yellow colorations. The oil diluted with alcohol acquires a reddish hue by ferric chloride.
The resin ammoniacum usually amounts to about 70 per cent. Przeciszewski asserts that the indifferent resin when heated yields sulphuretted hydrogen. Our own experiments failed to show the presence of sulphur in the crude drug; and the same negative result has been more recently obtained in some careful experiments by Moss[1240]. Water when boiled with the resin acquires a yellow hue and slightly acid reaction; the liquid assumes an intense red coloration on addition of ferric chloride.
Unlike the gum-resin of allied plants, ammoniacum yields no umbelliferone. When melted with caustic potash it affords a little resorcin.
The mucilaginous matter of the drug consists of a gum readily soluble in water and a smaller quantity of about ¼ of an insoluble part, no doubt identical with that occurring in asafœtida and galbanum. The aqueous solution of the gum of ammoniacum is very slightly levogyre.
Commerce—Ammoniacum is shipped to Europe from the Persian Gulf by way of Bombay. The exports from the latter place in the year 1871-72 were 453 cwt., all shipped to the United Kingdom. The quantity imported into Bombay in 1872-73 was 1671 cwt., all from the Persian Gulf.[1241]
Uses—The drug is administered as an expectorant and is also used in certain plasters.
Allied Gum-resins.
African Ammoniacum.—This is according to Lindley[1242] the product of Ferula tingitana L., a species growing over all northern Africa as far as Syria, Rhodus and Chios. It is called Kelth in Morocco, its product, Fasay, being shipped occasionally at Mazagan (el Bridja) or also at Mogador. This gum-resin is in large, compact, dark masses, formed of agglutinated tears having a whitish or pale greenish, or a fawn colour. But there are also seen very impure masses. The weak odour of the Moroccan drug is not suggestive of true ammoniacum. Moss (1873) found in a specimen of the former 9 per cent. of gum and 67 per cent. of resin. It yielded umbelliferone to Hirschsohn (1875), and by melting it with potash Goldschmiedt (1878) obtained Resorcin and a peculiar acid, C₁₀H₁₀O₆, which he failed to obtain from true ammoniacum.
Opopanax—A gum-resin occurring in hard, nodular, brittle, earthy-looking lumps of a bright orange-brown hue, and penetrating offensive odour, reminding one of crushed ivy-leaves. It is commonly attributed to Opopanax Chironium Koch, a native of Mediterranean Europe. We have never seen a specimen known to have been obtained from this plant; but can say that the gum-resin of the nearly allied Opopanax persicum Boiss., as collected by Loftus at Kirrind in Western Persia in 1851, has neither the appearance nor the characteristic odour of officinal opopanax. Powell,[1243] who endeavoured to trace the origin of the drug, regards it as a product of Persia.