Page:Popular Science Monthly Volume 39.djvu/440

426 cream is to aid its "ripening." Dairymen let their cream ripen before churning, because their experience shows that from such cream butter "comes" more readily, keeps better, and is of better flavor than from sweet cream. In a recent paper on this subject, Dr. H. W. Conn states that milk will become contaminated with bacteria if put into vessels in which particles of curd and grease are left sticking in joints and on the sides. Boiling in water will kill the bacteria, but their spores or seeds can not be killed without a higher heat. Hence, to prevent the souring of milk, cans and pans should be set on a stove or in the oven a few minutes after washing. As cold checks the development of bacteria, the milk should be cooled immediately after it is drawn from the cow, and kept as cool as possible. Cream for butter, on the contrary, should be kept in a warm place, so as to favor the growth of bacteria. Dairymen sometimes add a little old cream to a fresh lot as a leaven. Acid is also added for the same purpose, but this is of doubtful use.

A Fire-ball in Art.—In the Madonna painted by Raphael for Sigismondo dei Conti dal Foligno, the Virgin is represented as in the clouds, the clouds rest upon a rainbow, and under the bow is a red fire-ball. Assuming that the introduction of so unique a feature as a fire-ball in a painting of the Madonna is symbolic, Prof. H. A. Newton has inquired into the history of the subject. He finds that on the 4th of September, 1511, there fell near Crema, some leagues southeast of Milan, a number of stones, the results of the explosion of a meteorite, which are described by several authors; and he believes that Raphael intended to represent this aërolite in his painting. He seeks to interpret its meaning by finding what men thought of such phenomena. When the Ensisheim stone fell, nineteen years earlier than this one, near the lines separating the contending French and German forces, the Emperor Maximilian had the stone brought up to the castle, and held a council of state to consider what the fall meant. Sebastian Brant, in a poem describing the fall, speaks of the terror it caused to the Burgundians and French. Eleven years later, in 1503, Maximilian, in a proclamation appealing for aid, included the Ensisheim stone-fall among indications of divine favor. After the fall of 1511, although the papal forces were defeated in battle, the French were forced to withdraw in June, 1512, from Milan and northern Italy. It is natural, then, to suppose that Raphael in the picture united in his painting the fire-ball with the rainbow in order to symbolize divine reconciliation and assistance.

The Highest Mexican Volcano.—One of the results of the recent scientific expedition of Prof. Angelo Heilprin and his companions to Mexico was the establishment of Orizaba as the highest of the giant volcanoes of that country. The barometrical measurements of the four highest volcanoes gave for Orizaba, 18,205 feet; Popocatepetl, 17,523 feet; Iztaccihuatl, 16,960 feet; and Nevado de Toluca, 14,954 feet. In favor of the accuracy of the measurements, Prof. Heilprin refers to the quality of his registered aneroid barometer, which was tested and corrected at Philadelphia before and after starting, at Vera Cruz, and in the city of Mexico; and the fact that all the summits were ascended within three weeks, and were measured with the same instrument, during a period of atmospheric equability and stability which is offered to an unusual degree by a tropical dry season. The measurements bring up the question of what is the culminating point of the North American continent. The only other mountain than Orizaba that need be considered in this connection is Mount St. Elias, in Alaska. The measurements of this mountain, however, depart so widely from one another that we are not yet in a position to affirm, even within limits of a thousand feet or more, how nearly it approaches in height the Mexican volcanoes. The most usual figure in standard publications is 14,970 feet; Malespina found, by taking the angles from Port Mulgrave, 17,851 feet; Tebenkoff reduced this figure by somewhat more than 900 feet. Mr. Dall, in 1874, made angular measurements from four points, 69, 127, 132, and 167 miles away, that gave results varying from 18,033 to 19,596 feet. He does not place great confidence in any of them. In view of the broad divergence existing in the later measurements, and the