Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 4, 1802).djvu/295

265&#93; VEI periments on Fegetalles" &c. (8vo, 6s.), and also in Mr, Gough's " Experiments and Ohscrvafions on the Vegetatio7i of Seeds," inserted in the4lhvol. of the "Memoirs of the Jjiterary and Philosophical Society of Manchester." VEINS, in the animal body, are membranous canals, destined tor the purpose of re-conveying the blood from the arteries to the heart. They run chiefly by the sides of arteries, but more towards the sur- face ; and are, like these, composed of three membranes, namely, the interior coat, resembling the arte- rial ; the second, or cellular ; and the third, consisting of longitudinal fibres ; the whole being, however, of a more delicate texture, so that they are apt to rupture, in conse- quence of too great expansion. Farther, the veins are provided with numerous thin, semi-lunar valves, which prevent ihe return of the blood ; a circumstance that would otherwise frequently occur, from a want of muscular power in the venous system : hence, no pul- sation can take place in these ves- sels. The blood which they re- ceive from the arteries, flows but slowly to the heart j and is con- veyed thither by the contra6tilily of their membranes ; the propul- sion of the succeeding columns of that fluid from the arteries j the rontradion of the muscles ; and by the aft of respiration. In cases of venesedion by the lancet, the blood being geneially taken from the veins, we deem it a duty, to caution our readers against resorting to unskilful hands, where Buch an operation becomes neces- sary ; as, from the contiguity of the arteries, as well as the nerves and tendons, serious injuries may )e sustained^ &ad whipli^ in wmy VER [265 cases, have proved fatal, — If, dur- ing blood-letting, the patient be- come faint, it will be advisable to admit fresh air into the room ; to give mild cordials ; and to lay the person in a horizontal posture : by these means, the circulation will again be restored, and all farther inconvenience be obviated. For an account of the varicose aneurism, an aft"e6tion of the veins, we refer the reader to the article Aneurism, Velvet. LEAF. See Tree-mal- low. VENEERING, is a species of inlaying or marquetry, in which several thin leaves, or slips of fine wood, are applied to a ground- work of coniaion wood : it is per- formed in the following manner-; The wpod, intended for veneer- ing, is f)rst fixed in a vice, or saw- ing-press, where it is divided into leaves, not exceeding one line in thickness. Such leaves are then cut into small slips, of various forms, according to the design pro{)osed ; and, when the ground- work is duly prepared, they are cemented by means of glue, and submitted to the aftion of a press, till the whole becomes perfe6tly dry; after which the articles aro scraped and jx)lishcd. Ventilation, See vol. i. pp. 22 and 23; also the article Gka- NAKY. Venus-comb. See Needle, the Common Shepherd's, VEKDIGREASE, or Acetitb OF CoiTEK, is a kind of rust usu- ally prepared from that metal, by con'oding it with vinegar. The best verdigrease is mostly manufadurcd at Montpelier, in France, by forming alternate strata of copper-jjlales, and the husks of grapes, during tlwir vinous fermen- tation;