2. Osmium tetrachloride. (OsCl4). Syn. Osmic tetrachloride, Osmium bichloride. This may be procured in the same manner as the dichloride, using, however, an excess of chlorine. It occurs as a red, crystalline, fusible, deliquescent powder. It is more volatile than the dichloride. Both the dry chloride and the tetrachloride of osmium are dissolved by water, which decomposes them into tetroxide of osmium, hydrochloric acid and the metal.
OSTEOCOL′LA. A rough sort of glue or gelatin obtained from bones by digestion in dilute hydrochloric acid, to remove their earthy matter, and afterwards acting on the residuum with water at a high temperature, until it is wholly dissolved.
OTAL′GIA. Pain in the ear. See Earache.
O′′THYL. In chemistry, a radicle having the formula C2H3O, assumed by Professor Williamson to exist in acetic acid.
OT′TO OF ROSES. See Oils (Volatile).
OVALBU′MEN. White of egg; to distinguish it from seralbumen, or the albumen of the serum of the blood.
O′VENS. A very ingenious and useful improvement in the apparatus for baking was introduced some years ago by Mr Sclater, of Carlisle. It consists in causing the articles to be baked to traverse a heated earthenware tube. This tube forms the oven. It is of considerable length, and the biscuits or other articles are slowly traversed through it, from end to end, at such a rate as will allow of the baking being completed during the passage. The biscuits are carried on trays, set on travelling chains; or the trays are made into an endless web or chain. The oven is thus entirely self-acting, and the articles demand no
attention whatever from the attendants, whilst the system combines superior economy with the best results. A ‘pyrometer,’ or heat indicator, is attached externally, so that the attendant can regulate the heat with great facility. The object of these improvements is to reduce the cost of baking, and to improve the appearance of the baked articles. The apparatus is applicable as well to the baking of articles of clay or earthenware as to bread or biscuits.
Of the ovens now in common use by the bakers, that known as the ‘hot-water oven’ is perhaps the best; not merely in reference to economy, but also with reference to its superior cleanliness, and the ease with which the articles operated on may be turned out of that delicate yellowish-brown tint for which the bread of the Viennese and Parisian bakers is so celebrated. See Baking, Bread, &c.
OWNER. For the purposes of the Public Health Act this term is thus defined:—“‘Owner’ means the person for the time being receiving the rack-rent of the lands or premises in connection with which the word is used, whether on his own account, or as agent or trustee for any other person, or who would so receive the same if such lands or premises were let at a rack-rent.”