Consequently the freezing point of water, or the melting point of ice (32° F.), is taken for one of the fixed points in thermometry. The freezing point of mercury is 39° below zero, of sulphuric ether 46° below zero, of alcohol 203° below zero F. How is Fresco Painting Done? In producing fresco paintings, a finished drawing on paper, called a cartoon, exactly the size of the intended picture, is first made, to serve as a model. The artist then has a limited portion of the wall covered over with a fine sort of plaster, and upon this he traces from his cartoon the part of the design suited for the space. As it is necessary to the success and permanency of his work that the colors should be applied while the plaster is yet damp, no more of the surface is plastered at one time than what the artist can finish in one day. A portion of the picture once commenced, needs to be completely finished before leaving it, as fresco does not admit of retouching after the plaster has become dry. On completing a day’s work, any unpainted part of the plaster is removed, cutting it neatly along the outline of a figure or other definite form, so that the joining of the plaster for the next day’s work may be concealed. The art is very ancient, remains of it being found in India, Egypt, Mexico, etc. Examples of Roman frescoes are found in Pompeii and other places. After the beginning of the fifteenth century fresco painting became the favorite process of the greatest Italian masters, and many of their noblest pictorial efforts are frescoes on the walls of palaces and churches. Some ancient wall paintings are executed in what is called “Fresco Secco,” which is distinguished from true fresco by being executed on dry plaster, which is moistened with lime water before the colors are applied. Fresco painting has in recent years again been revived, and works of this kind have been executed in the British Houses of Parliament and other public and private buildings, more especially in Germany. The Story of a Piece of Chewing Gum[26] The original “chewing gum” was spruce gum, the exudation of the cut branches of the spruce or fir tree. Later, pure white paraffin wax, variously flavored, took its place, but only in its turn to give way to the “chicle” now almost exclusively employed. Though its employment in the manufacture of chewing gum is of comparatively recent date, chicle was used by the Indians prior to the days of Columbus as a means of quenching their thirst. It was first commercially imported as a substitute for rubber, but its peculiar suitability for chewing gum has resulted in the entire product being consumed by that industry. In 1885 the United States imported 929,959 pounds of chicle. The growth of the chewing gum industry is shown by the importation of nearly 5,500,000 pounds for the year ending with June 30, 1910.