ROSA, Medical Properties of. Of the numerous species or varieties of this genus, three only are indicated in the Pharmacopoeia' as the sources of the officinal articles ; but a very considerable number of them contribute the different materials. Those indicated in the Phannacopccia' are: the Rosa canine, or common (log-rose; Rosa gallica, the French or red rose; and Rosa centifulia, the hundred-leaved or cabbage-rose. Of the first, the so-called fruit (hips) is the officinal part This is truly the enlarged persistent calyx, enclosing the real fruits, which are numerous small achenia, clothed, as well as the inside of the calyx, with silky hairs. The hairs and achenia are to be care fully removed, and the fleshy calyx beaten into a pulp, to which gradually thrice their own weight of white sugar is to be added. The employment of heat in the preparation of this conserve, though directed by the Phartnacopeeia,' is better omitted. The pulp consists chiefly of inalie and citric acids, in combination mostly with some salts, tannin, resins, a small quantity of volatile and fixed oils, fibre, and a large quantity of sugar. The action on the stomach is slightly refrigerant and aperient, its sweetness recommending it to children, and as a vehicle for other medicines. It is apt to candy or concrete by keeping. The fresh hips, freed from the fruits and hairs, bruised, and having a little sugar added, yield, by pouring warm water upon them, a cooling mildly astringent drink, which would be grateful to the poor suffering from autumnal fevers.
The petals of both the Rosa gallica and R. damascene are supplied to herbalists for medical and chemical purposes. The latter is most extensively cultivated at Dlitcham for the London market. The buds are collected before they expand, and the calyx and lower part of the petals, termed claws, being cut off, they are quickly dried. If this last be conducted slowly; it impairs both their astringency and fine odeaa colour Their astringency and odour are greatest when col lected before the process of anthesie, or bursting of the anthers.
About 2000 flowers yield 100 lbs. of fresh petals, which when dry weigh only 10 lbs. After drying the odour is faint, the taste bitter and astringent. As by exposure to the light and air they lose their tine colour, and soon become mouldy or worm-eaten, they must be carefully preserved in well-stopped bottles or canisters.
According to the analysis of Cartier, they consist of volatile oil, colouring matter, fatty matter, gallic acid, tannin, albumen, soluble salts of potash, insoluble salts of lime, silica, and oxide of iron. The tannic and gallic acids are the cause of the astringency, and also of the dark colour, which results on adding a solution of any salt of iron to an infusion of roster, and of a slight precipitate when a solution of gela tine is added to the infusion. The property of forming a black com pound with iron is taken advantage of by beating the petals with doves and other spices in an iron mortar, till a thick black paste.is formed, which hardens on exposure to the air, and is then polished or turned, PO as to form the perfumed beads for necklaces or rosaries. The petals of II. centifolia are often preferred. Tho exact nature of the colouring principle lute not been ascertained, but it is not owing to oxide of iron, as the luantity of iron is much greater in white than red roma, Cartier having obtained from 1000 grains of white roses 99 grains of ashes, containing 121 of iron, while a similar quantity of reel roses yielded only 50 grains of ashes, containing only 4 grains of iron.
The petals of the Rosa damascene are the most laxative, except perhaps the R. semperflorens, but it is seldom that they are used as aperients, though the petals of the R. gallica are formed into a con fection which has the advantage over that of the R. canine, inasmuch as it neither candies nor becomes mouldy. In forming this or the other preparations, a stone (not an iron) mortar must be used. The chief employment of the conserve of the Gallic rose is as a vehicle for other medicines and as the basis of blue pill.