Ammoniacum Pharm. Lond. Gummi Ammoniacum Pharm. Edinb. Gum ammoni-acum: a concrete gummy resinous juice; brought from the East Indies (a); generally in large masses, composed of little lumps or tears, of a milky whiteness: the exteral parts of the mass are commonly yellowish or brownish, and the white tears change to the same colour on being exposed for some time to the air. Of the plant, from which it is extracted, we have no further knowledge, than what is learnt from the seeds found among the tears; which referable those of dill, except that they are larger, and apparently belong to a plant of the umbelliferous kind.

(a) From Egypt, according to Bergius. Mat. Med. p. 889. in Ammoniaci purificatio ph. Lond.

Ammoniacum has a strong smell, like that of galbanum, but less ungrateful, and a nau-seous sweetish taste which is followed by a bitter one. Its principal virtue is that of resolving obstructions; in which intention, it is frequently made use of in asthmas and difficulty of expectoration, in menstrual suppressions, and cachectic indispositions. In obstructions of the bread, it is accounted the most effectual of the aperient gums: in hysteric cases, some of the others are preferred or joined to it, on account, chiefly, of their more powerful smell. It is most com-modiously taken in the form of pills: the dofe is a scruple or half a dram, every night or oftener: in larger doses, as a dram, it generally loosens the belly. Applied externally, it is supposed to discuss hard indolent tumours.

It is purified from the seeds, small stones, etc. commonly intermixed among the tears, by softening or dissolving it in a little boiling water, pressing it, whilst hot, through a drainer, and then infpiffating it to its former consistence. For internal use, the larger and finer tears, un-purified, are preferable to the common drained gum; for unless the process be very skilfully managed, it loses in the purification great part of its smell, and not a little of its taste. In the shops, a composition of much inferiour virtues has been often fold in the room of strained am-moniacum.

Ammoniacum, triturated with water, dis-solves into an emulsion or milky liquor, and in this form acts rather more effectually than in the solid one of a pill. Simple penny-royal water is commonly employed for this purpose, in such proportion, that four spoonfuls (that is, two ounces) of the emulsion contain thirty grains of the ammoniacum. Some have dis-solved it in vinegar of squills, and thus obtained an expectorant undoubtedly powerful, though more unpalatable.

If the milky solutions are kept some time, they deposite a considerable quantity of resinous matter, and become clear. Infpiffated, they yield an extract, of no smell, and of only a weak bitterish taste. In distillation, no essential oil is obtained, and the distilled water is but slightly impregnated with the flavour of the ammoniacum. In this respect, ammoniacum differs remarkably from most of the other de-obstruent gums, as afafetida, galbanum, and fagapenum, which afford not only a strong distilled water, but an actual oil containing the concentrated flavour of the gums.

Rectified spirit of wine dissolves near one half of ammoniacum into a transparent reddish yellow liquor, which tastes strongly of the drug: the undissolved mucilaginous matter is nearly insipid. On distilling the filtered tincture by a gentle heat, the spirit which comes over has hardly any flavour of the ammoniacum: never-theless the remaining extract proves weaker, both in smell and taste, than the juice in substance.

Lac ammo-niaci Ph.