Page:Popular Science Monthly Volume 47.djvu/296

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The meteorological station on the Misti was successfully conducted for several months, one of the assistants visiting it every ten days and readjusting the self-recording instruments, till the station was broken into by Indians and some of the instruments were carried off.-Long-exposure photographs were taken at Arequipa of three nebulæ and clusters under an improved method by which certain errors due to flexure and refraction are corrected. The great advantages of the atmospheric conditions at Arequipa are insisted upon. With the Bruce photographic telescope the spectra of the faint stars prove very satisfactory; and stars too faint to be photographed with other instruments can thus be studied. Experiments have been made to determine the photographic magnitudes of the brighter stars on a uniform scale.

The New Element in the Atmosphere, Argon.—The real existence of the new element which Lord Rayleigh and Prof. Ramsay claim to have discovered in the atmosphere appears to be proved by further investigations, of which, and of the substance itself—named argon—the discoverers recently gave a full account at the University of London before the members of the Royal Society. The discovery seems to have been first made by Lord Rayleigh in the course of his experiments for the determination of the densities of some of the more permanent gases. He found that nitrogen obtained from chemical compounds was about a half per cent lighter than when obtained from the atmosphere. Prof. Ramsay took up the investigation with Lord Rayleigh's permission. Both achieved the separation of argon from nitrogen; Prof. Ramsay by a chemical method, and Lord Rayleigh by the process of "sparking." It has now been separated from the air by atmolysis—a kind of filtering process applied to gases—by red-hot magnesium, and by sparking. Its density has been determined to be about 19·7. It is very soluble in water, and it has been proved that the nitrogen extracted from rain-water is twice as rich in argon as that which exists in the air. Argon is best obtained by freeing the air, from which carbonic acid and water have been removed, from oxygen by means of red-hot copper and then absorbing the nitrogen by means of metallic magnesium, which, when heated to redness, combines with the nitrogen, forming an orange-colored mass of magnesium nitride. The residual gas after this series of operations—the passage of the gases being repeated again and again—is argon. In this process chemically derived nitrogen yields no snch residue. The density of pure argon is 20 (19-7); hence its molecular weight, in accordance with Avogadro's law, must be 40. There are reasons for believing that, like mercury, its molecule contains but one atom; its atomic weight, 40, is therefore identical with its molecular weight. Argon is soluble to the extent of four volumes per one hundred volumes of water, so that it is about two and a half times as soluble as nitrogen, and possesess approximately the same degree of solubility as oxygen, and is accordingly found to occur in increased proportion to nitrogen in rainwater. According to Dr. Olszewski, argon easily condenses to a colorless liquid at a temperature of —128·6º C. and under a pressure of thirty-eight atmospheres. At a lower temperature argon freezes to a crystalline mass like ice; at a still lower temperature it becomes white and opaque. Its freezing point is —189·6º, its boiling point —187º, and its density as a liquid is 1·5. Mr. Crookes has found that it has two spectra, marked by red and blue lines respectively. This indicates that it may be a mixture of two elements. Other properties indicate that it is a single element, and the weight of the evidence seems so far to be in favor of this supposition. There are difficulties in the way of the unqualified acceptance of either view. It presents other problems of constitution and behavior, in view of which much study will yet be required before a satisfactory conception can be gained of its exact nature and of its place in the chemical series. It is chemically the most inert element yet found.

Distinction of Animals and Plants.—Finding that the definitions of the distinctions between animals and plants fail when the attempt is made to apply them to the lower organisms, Prof. Charles S. Minot suggests, in Science: "Animals are organisms which take part of their food in the form of concrete particles, which are lodged in the cell protoplasm by the activity of the protoplasm itself. Plants are organisms