AMMOS, in anatomy, a thin pellucid membrane, which surrounds the fixtus.
The fcctus in the uterus is enveloped in a peculiar membranaceous covering, to which anatomists hare given the name of amnios. Within this there is a liquid, distinguished by the name of the liquor of the amnios, which surrounds the fcetus on every part. This liquid, as might hal e 'seen expected, is very different in dif ferent animals; at least the liquor amnii in women and in cows, which alone hare hitherto been analysed, have not the smallest resemblance to each other. The liquor of the amnios of women is a fluid of a slightly milky colour, a weak plea sant odour, and a saltish taste. The white colour is owing to a curdy matter suspended init, for it may be obtained quite transparent by filtration. Its spe cific gravity is 1.005. It gives a green colour to the tincture of violets, and yet it reddens very- decidedly the tincture of turnsole. These two properties would in dicate at once the presence ofan acid and of an alkali. It froths considerably when agitated. On the application of heat it becomes opaque, andhas then a great re setnblance to milk diluted with a litrge quantity of water. At the same time it exhales the odour of boiled white of egg. Acids render it more transparent. Alka lies precipitate an animal matter in small flakes. Alcohol likewise produces a flaky precipitate, which, v.iten collected and dried, becomes transparent and very like glue. The infusion of nut galls pro duce.s a very copious brown coloured precipitate. Nitrate of silver occasions a white precipitate, which is insoluble in nitric acid, and consequently is nuiriatc of silver. The liquor of the aninios of
the cow has a viscidity similar to mucil age of gum arable, a brownisl red colour, an acid and bitter taste, and a peculiar odour, not unlike that of some vegetable extracts. Its specific gravity is 1.028. It radens the tincture of turnsole, and therefore contains an acid. Muriate of' barytes causes a very abundant precipi tate, which renders it probable that it contains sulphnric acid. Alcohol sepa rates from it a great quantity of a reddish coloured matter. The animal matter posses'ses the following properties : It has a reddish bron n colour and a peculi ar taste ; it is very soluble in water, but insoluble in alcohol, Which has the pro perty' of separating it from water. When exposed to a strong heat, it swells, ex: hales first the odour of burning gum, then of empyreumatic oil, and of ammonia, and at last the peculiar odour of prussic acid becomes very conspicuous. ft dif fers from gelatine in the viscidity which it communicates to water, in not forming a jelly v.-hen concentrated, and in not be ing precipitated by tannin. It niust be therefore ranked among the very unde fined and inaccurate class of animal muci lages. When burnt, it leaves alarge por tion °fermi, which is readily incinerated, and leaves a little white ashes,,composed of phosphate of magnesia, and a small proportion of phosphate of lime.