ton and linen rags stand at one extreme and wood pulp at the other. The destructive agents are oxygen, the action of which is stimulated by resins used in sizing the paper; water, which provokes chemical changes that are facilitated by acid substances present in the sizings; and living organisms—molds and bacteria—which become more dangerous than ever when gelatin is introduced into the sizing. Paper must further possess mechanical qualities to enable it to endure—strength, a certain degree of elasticity, and resistance to rubbing and friction—all of which are involved in the questions of material and sizing. Then all papers are "filled" or "loaded," generally with clay, to give them "body" and opacity and to cheapen the manufacture. This does not actually injure the paper, but may be carried to such an extreme as to be a cheat. The best papers, and the only ones suitable for use in permanent records, are those made of what Messrs. Cross and Bevan, in their book fully treating of the subject, call normal cellulose—cotton and linen—with china clay only sparingly used. Such papers are now, unfortunately, rare. China clay is prodigally used, and wood and straw largely take the place of rags. Papers made of these substances are very inferior and perishable. They are easily liable to discoloration, oxidize readily and gradually crumble, rot, and perish—a fact of which any one may satisfy himself by looking at some newspaper cuttings only a few years old. The conclusion is drawn by Mr. C. F. Cross, from the examination of specimens of serial publications in various European languages, that "a large proportion of the literary and scientific work of the age is printed on an extremely perishable foundation." Happily, publishers have become aware of this deficiency of modern papers and are exercising more care in the selection of those to be used in their better works; and manufacturers claim that with improved processes and better methods they are able to make even wood paper that will last.
More New Elements in the Atmosphere.—In communications to the French Academy of Sciences and the Royal Society, Prof. William Ramsay has reported the discovery by himself and Mr. M. W. Travers of still other hitherto undetected elements in the atmosphere. The author, "having obtained a quantity of liquefied air from Dr. Hamps on, allowed it to cool and evaporate slowly till only about ten cubic centimetres remained out of the original quantity of seven hundred and fifty cubic centimetres. The gas obtained from this residue was then carefully purified from oxygen and nitrogen, and when examined spectroscopically showed the argon spectrum freely and also another spectrum which was believed never to have been seen before, especially characterized by the presence of two very brilliant lines, one in the yellow, close to but not identical with the helium line, and another in the green. Other lines were also seen, but they were much less intense. The new spectrum is under special study by Mr. Baly. The newly discovered gas is less volatile than nitrogen, oxygen, and argon, and heavier than argon, having a density measured at 22.5 as compared with hydrogen, but likely to prove greater when it is obtained free from argon. The ratio of its specific heats indicates that it is monatomic, and therefore an element. Professor Ramsay proposes for it the name krypton (concealed) and the symbol Kr. In a subsequent communication to the Royal Society, Professor Ramsay and Mr. Travers reported that on submitting argon to liquefaction, a colorless liquid was obtained with a white solid substance condensing partly around the sides of the tubes and partly below the surface of the liquid. A gas was obtained from the liquid by distillation and collected in two fractions. The spectrum of the gas was characterized by a number of bright red lines, one of which was particularly brilliant, and a brilliant yellow line, while the green and blue lines were numerous but not conspicuous. The measured wave length of the yellow line showed that it is not identical with those of sodium or helium, which equal it in intensity. Density measurements gave 17.2 for the first fractionation and 14.7 for the second—a result that encourages hopes that when obtained in greater purity it may have the density of about 11 requisite to give it a place in the periodic table. The name neon is proposed for this new gas. The white solid substance which was obtained with the liquid argon volatilized slowly, but on wiping off the coating of snow from the bulb with the finger was seen to