3. (Purple.)—a. Steep litmus in water, and strain the solution.—b. Add a little alum to a strained decoction of logwood.—c. Add a solution of carmine (red) to a little blue solution of litmus or Saxon blue.
4. (Red.)—a. Macerate ground Brazil wood in vinegar, boil a few minutes, strain, and add a little alum and gum.—b. Add vinegar to an infusion of litmus until it turns red.—c. Boil or infuse powdered cochineal in water containing a little ammonia or sal volatile.—d. Dissolve carmine in liquor of ammonia, or in
weak carbonate of potash water; the former is superb.
5. (Yellow.)—a. Dissolve gamboge in water, and add a little alum.—b. Dissolve gamboge in equal parts of proof spirit and water. Golden coloured.—c. Steep French berries in boiling water, strain, and add a little alum.—d. Steep turmeric, round zedoary, gamboge, or annotta, in a weak ley of subcarbonate of soda or potash.
Obs. The preceding, thickened with a little gum, are used as inks for writing, as colours to tint maps, foils, paper, artificial flowers, &c., and to paint on velvet. Some of them are very beautiful. Those containing litmus are, however, fugitive. It must be observed that those made with strong spirit do not mix well with gum water, unless somewhat diluted with water. Any other transparent colours or stains may be employed for painting on velvet, as well as the above.
VELVET LEAF. Syn. Pareira brava, Pareira (Ph. L., E., & D.) L. “The root of Cissampelos pareira” (Ph. L.), white pareira or velvet leaf. It is tonic, aperient, and diuretic.—Dose, 20 to 60 grains; in chronic and purulent inflammation and extreme irritability of the bladder; in leucorrhœa, dropsy, ulceration of the kidney, &c.
VENESECTION. The practice of venesection, bloodletting, or phlebotomy, as it is variously denominated, has within the last thirty or forty years been nearly banished from medical practice. It seems very evident that prior to the above period medical practitioners were in the habit of resorting to venesection to an unwise extent, and in cases which the progress of modern pathology has shown it to be wholly inapplicable.
There are, we believe, some practitioners who, whilst admitting the evils arising from its misapplication and abuse, still advocate its occasional and judicious employment.
Because of the dangers that beset the operation when performed by a tyro, we forbear to give any particulars as to the method of carrying it out. The veins of the arm are those always invariably opened in venesection, although the operation may be performed on many other superficial veins.
VEN′ISON. The flesh of several species of deer. That from good land, killed at the proper season, and eaten in a moderately fresh state, is most easily digestible, and, perhaps, the most wholesome, of all the red meats; but when it is ‘high,’ or in a state of incipient putrefaction, it is far from wholesome, and often poisonous.