Botanical Origin—Dorema Ammoniacum, Don, a perennial plant,[1229] with a stout, erect, leafless flower-stem, 6 to 8 feet high, dividing towards its upper part into numerous ascending branches, along which are disposed on thick short stalks, ball-like simple umbels, scarcely half an inch across, of very small flowers. The aspect of the full-grown plant is therefore very unlike that of Ferula. The Dorema has large compound leaves with broad lobes. The whole plant in its young state is covered with a tomentum of soft, stellate hairs, which give it a greyish look, but which disappear as it ripens its fruits. The withered stems long remain erect, and occurring in immense abundance and overtopping the other vegetation of the arid desert, having a striking appearance.[1230] The root is described in the article on Sumbul, [p. 313].
The plant occurs over a wide area of the barren regions of which Persia is the centre. According to Bunge and Bienert, its north-western limit appears to be Shahrud (S.E. of Asterabad), whence it extends eastwards to the deserts south of the Sea of Aral and the Sir-Daria. The most southern point at which the plant has been observed is Basiran, a village of Southern Khorassan in N. lat. 32°, E. long. 59°.
Of the three or four other species of Dorema, D. Aucheri Boiss.[1231] affords very good ammoniacum, as we know by an ample specimen of the gum deposited together with the plant in the British Museum by Mr. W. K. Loftus, who in 1751 collected both at Kirrind in Western Persia, where the plant is called in Kurdish Zuh. Boissier[1232] includes as D. Aucheri another plant, called by Loftus D. robustum, the gum of which is certainly different from ammoniacum. Of the plant itself there are only fruits in the British Museum.
History—The first writer to mention ammoniacum is Dioscorides, who states it to be the juice of a Narthex growing about Cyrene in Libya, and that it is produced in the neighbourhood of the temple of Ammon. He says it is of two sorts, the one like frankincense in pure, solid tears, the other massive, and contaminated with earthy impurities. Pliny gives essentially the same account.
The succeeding Greek and Latin authors on medicine throw but little light on the drug, which however is mentioned by most of them as used in fumigation. Hence we find such terms as Ammoniacum thymiama,[1233] Ammoniacum suffimen, Thus Libycum.
The African origin assigned to the drug by Dioscorides, has long perplexed pharmacologists; but it is now well ascertained that in Morocco a large species of Ferula yields a gum-resin having some resemblance to ammoniacum, and still an object of traffic with Egypt and Arabia, where it is employed, like the ancient drug, in fumigations. There can be but little doubt we think, that the ammoniacum of Morocco is identical with the ammoniacum of the ancients; it may well have been imported by way of Cyrene from regions lying further westward.[1234]
Persian ammoniacum or the ammoniacum of European commerce may also have been known in very remote times, though we are unable to trace it back earlier than the 10th century, at which period it is mentioned by Isaac Judæus[1235] and by the Persian physician Alhervi.[1236] Both these writers designate it Ushak, a name which it bears in Persia to the present day.
Collection—The stem of the plant abounds in a milky juice which flows out on the slightest puncture. The agent which occasions the exudation is a beetle, multitudes of which pierce the stem. The gum, the drops of which speedily harden, partly remains adherent to the stem and partly falls to the ground; it is gathered about the end of July by the peasants, who sell it to dealers for conveyance to Ispahan or the coast.[1237]
Young roots 3 to 4 years old are, according to Borszczow, extremely rich in milky juice which sometimes exudes into the surrounding soil in large drops; there is also an exudation from the fibrous crown of the root of a dark inferior sort of ammoniacum. The gum-resin appears to be collected in quantity only in Persia. One of the chief localities for it are the desert plains about Yezdikhast, between Ispahan and Shiraz.
Description—Ammoniacum occurs in dry grains or tears of roundish form, from the size of a small pea to that of a cherry, or in nodular lumps. They are externally of a pale creamy yellow, opaque and milky-white within. By long keeping, the outer colour darkens to a cinnamon-brown. Ammoniacum is brittle, showing when broken a dull waxy lustre, but it easily softens with warmth. It has a bitter acrid taste, and a peculiar, characteristic, non-alliaceous odour. It readily forms a white emulsion when triturated with water. It is coloured yellow by caustic potash. Hypochlorites, as common bleaching powder, give it a bright orange hue, while they do not affect the Morocco drug.