The milky juice is neutral and coagulates rapidly, separating in two parts: a kind of insoluble pulp and a limpid colorless serum. If combined with fibrin, raw meat, white of egg or gluten it gradually softens them and completely dissolves them in 3 or 4 hours _in vitro_ at 40° C. Combined with milk it coagulates it and soon precipitates the casein which is also dissolved a little later. It digests lumbricoids and tape-worms and the false membrane of croup, in a few hours. According to Wurtz and Bouchut papain is prepared as follows: The fluid juice or the aqueous solution of the milky exudate is precipitated by the addition of ten times the volume of alcohol. The precipitate, after treating again with concentrated alcohol, is dissolved in water and the addition of sub-acetate of lead eliminates the albuminoids and peptones but does not precipitate the papain. The liquid is filtered and the lead salts separated by means of a current of hydrogen sulphide. It is filtered again and alcohol added gradually, which process first precipitates whatever sulphate of lead may have passed through the filter, and then the papain. Papain is an amorphous substance, perfectly white, soluble in water, insipid, odorless. An aqueous solution, if shaken violently, foams like a solution of soap. Boiling makes it turbid and when concentrated it has a slightly astringent taste. It is precipitated by hydrochloric, nitric, picric and the metaphosphoric acids. Trommer's test gives it a beautiful blue violet color which, on boiling, changes to a red violet. It is an extremely active digestive ferment, comparable with pepsin, but superior to the latter because it does not require an acid medium, as its digestive action takes place even in the presence of an alkaline medium and of antiseptic substances such as boric acid, phenol, etc. It is given in doses of 10-40 centigrams in different vehicles such as water, wine, etc. It should be given after meals carefully and properly diluted, in order that its action may not be exerted upon the gastric mucous membrane itself. Its use is contraindicated in gastric ulcer. A watery solution prepared by macerating the green fruit has been used effectively to remove blemishes from the face, leaving the skin clean and smooth. The natives use little pieces of the green fruit to remove freckles (which they call _pecas_). The ripe fruit is edible and its taste quite agreeable; in some of the Malay Islands it is given for dysentery, but it must be remembered that the ripe fruit does not contain papain.