For removing the wax covering with which the bees close the full cells a peculiarly shaped knife, known as an uncapping knife, is needed (figs. 34 and 35). The blade, which should be of the finest steel to hold a keen edge, is fixed at such an angle with the handle as to keep the hand that grasps the latter from rubbing over the surface of the comb or the edges of the frames. The form of knife with curved point is best adapted to reach any depression in the comb, which, if uncapped and emptied of its honey, will likely next time be built out even with the general surface. Dipping the knife in hot water facilitates rapid work, and of course the heavier-bladed knives hold the heat better than thin bladed ones, and are for this reason preferred by some; also because they more surely lift the capping clear from the surface of the comb. WAX EXTRACTORS. A solar wax extractor is needed in every apiary; several are kept running in many large apiaries. Extractors which render wax by steam are also used. To the latter class belongs the improved Swiss wax extractor (fig. 36). This implement, invented in Switzerland and improved in America, consists of a tin or copper vessel with a circle of perforations in the bottom near the sides to let in steam from a boiler below, and within this upper vessel another receptacle--the comb receiver--made of perforated zinc. Its use, as well as that of the solar wax extractor, is described under the head of "Wax production." [Illustration: Fig. 36.--Excelsior wax extractor.] Within a few years wax extractors employing the heat of the sun and known as solar wax extractors have come into general use (fig. 61). The essential features in all the forms that have been devised are a metal tank with a glass cover and usually a wire-cloth strainer, below which is placed the receptacle for the wax, the whole so arranged as to enable one to tilt it at such an angle as will catch the direct rays of the sun. The effectiveness of the solar wax extractor is increased by having the glass doubled, and adding also a reflector, such as a mirror or a sheet of bright metal. An important advantage of the solar wax extractor is the ease with which small quantities of comb can be rendered. By having this machine much is therefore saved that might be ruined by wax moth larvæ if allowed to accumulate, besides serving at the same time to increase these pests about the apiary. The wax obtained by solar heat is also of superior quality, being clean, never water-soaked nor scorched, and also light in color, owing to the bleaching action of the sunlight. The cost of a medium-sized solar wax extractor does not exceed that of the larger Swiss steam extractors, yet of the two the former is likely to prove by far the more valuable, even though it can be used only during the warmer months. QUEEN-INTRODUCING CAGES.