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THE POPULAR SCIENCE MONTHLY. 



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 in- 

 struments, 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 nebulae 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 in- 

 sisted 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 magni- 

 tudes of the brighter stars on a uniform 

 scale. 



The New Element in the Atmosphere, 

 Argon. The real existence of the new ele- 

 ment which Lord Rayleigh and Prof. Ramsay 

 claim to have discovered in the atmosphere 

 appears to be proved by further investiga- 

 tions, of which, and of the substance itself 

 named argon the discoverers recently gave a 

 full account at the University of London be- 

 fore the members of the Royal Society. The 

 discovery seems to have been first made by 

 Lord Rayleigh in the course of his experi- 

 ments 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 at- 

 molysis a kind of filtering process applied to 

 gases by red-hot magnesium, and by spark- 

 ing. Its density has been determined to be 

 about 197. It is very soluble in water, and 

 it has been proved that the nitrogen extract- 

 ed 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 ni- 

 tride. 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 ac- 

 cordance 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 rain- 

 water. According to Dr. Olszewski, argon 

 easily condenses to a colorless liquid at a 

 temperature of 128"6 C. and under a pres- 

 sure 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 189'6, its boiling point 187, 

 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 indi- 

 cates that it may be a mixture of two ele- 

 ments. Other properties indicate that it is 

 a single element, and the weight of the evi- 

 dence 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 con- 

 ception 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 distinc- 

 tions between animals and plants fail when 

 the attempt is made to apply them to the 

 lower organisms, Prof. Charles S. Minot sug- 

 gests, 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 



