Rennet, Liquid. Syn. Essence of rennet. Fresh rennet, 12 oz.; salt, 2 oz.; proof spirit, 2 oz.; white wine, a quart; digest for 24 hours and strain. A quart of milk requires 2 or 3 teaspoonfuls. Wislin directs 10 parts of a calf’s stomach; salt, 3 parts. The membrane of the stomach is to be cut with scissors and kneaded with the salt, and with the rennet found in the interior of that organ; the whole left in a cool place in an earthen pot till the cheesy odour is replaced by the proper odour of rennet, which will be in one or two months. Then add 16 parts of water and 1 of spirit. Filter and colour with burnt sugar.
The German Pharmacopœia gives the following formula for liquid rennet:—3 parts of the mucous membrane of fresh calf’s rennet, macerated for three days in 26 parts of white wine, 1 part of table salt being added.
Obs. 2 or 3 teaspoonfuls will curdle a quart of milk. Some persons use white wine instead
of water, with simple digestion for a day or two.
RES′IN. Syn. RESINA, L. This name is applied to many vegetable principles composed of the elements carbon, hydrogen, and oxygen. The resins (RESINÆ) cannot be very accurately defined, but we may in a general way describe them as substances which are solid at ordinary temperatures, more or less transparent, inflammable, readily fusible, do not volatilise unchanged, become negatively electrified by rubbing; are insoluble in water, but soluble in alcohol; mostly inodorous, and readily incorporated with fatty bodies by fusion. Their sp. gr. varies from ·9 to 1·2. According to Liebig, they are oxidised essential oils. Common resin, rosin, or colophony, and the shellac of which sealing-wax is made, are familiar examples of these substances. (See below.)
Resin, Black. Syn. Rosin‡, Black r.‡, Colophony; Resina nigra, Colophonia, L. What remains of turpentine after the oil has been distilled. When this substance, whilst still fluid, is agitated with about 1-8th part of water, it forms the yellow resin of pharmacy. Used for violin bows, dark-coloured ointments, varnishes, &c.
Resin, Yel′low. Syn. Yellow rosin‡, White r.‡; Resina flava, Resina (Ph. L.), La. Detergent. Used in ointments, plasters, &c. (See above.)
RES′INOIDS. Syn. Resinous extracts, Concentrated e.; Extracta resina, L. Under this head, the so-called ‘Eclectics,’ who form a numerous class among American physicians, place their most important ‘concentrated remedies.’ “Viewed as pharmaceutical preparations eligible for use in medicine, though not purified so as to rank as distinctive proximate principles, these are very appropriately named ‘resinous extracts,’ or ‘resins.’ The term ‘resinoid,’ so commonly used, is less appropriate to the class, implying, as it does, a resemblance to resins, while all of these are either resins, oleo-resins, or more or less mixed proximate principles possessing no real resemblance to the class of resins.” (Parrish.) Most of them are prepared from plants indigenous to North America, by precipitating a strong alcoholic tincture with water. They are all brought to the condition of powder, those which are naturally soft and oily being mixed with a sufficient quantity of sugar of milk, or other dry material. One of these eclectic remedies has been introduced into regular practice. See Podophyllin.
RESIN, or ROSIN OIL. This is a product of the dry distillation of resin. The apparatus used consists of an iron pot, a head piece, a condensing arrangement, and a receiver.
In distilling the resin, a bright oil first comes over with water. As soon as a cessation in the flow of the distillate occurs the receiver is changed, and the heat is further raised, when a red-coloured and heavy rosin oil comes over. The black residue remaining