Z7^ 



NATURE 



[August i6, 1900 



of the fire and of the subsequent state of the wooden 

 backing led to a number of interesting conclusions as to the 

 value of the protection afforded by various retardent materials. 

 Among these we note the comparative value of a wooden and 

 metallic lath ; the necessity of applying fire retardent material 

 in at least two thicknesses so as to break joints ; the immense 

 superiority of three-ply over two-ply doors ; the advantage of the 

 Atkinson composite door as being more gas-tight than a wooden 

 door ; the fire-resisting qualities of three-inch plank as compared 

 with one-inch boards, or lath and plaster ; the excellency of 

 Mississippi wire glass ; and the satisfactory performance of 

 •' King's Windsor " cement and " Adamant " plaster. 



An important development of the electron theory has been 

 carried out by Robert Lang in his article on atomic magnetism 

 contributed to the Annalen der Physik (No. 7). It may now be 

 said that the phenomena of magnetism have at last been 

 successfully reduced to those of electricity. We know from the 

 work of Thomson and of Drude that an electric current in 

 a wire consists of a stream of very small particles called 

 electrons. These electrons are formed by the splitting up 

 of the metallic atoms into a larger positive and a smaller 

 negative portion. The positive electrons, under the influence 

 of an eleccromotive force, travel in one direction along the 

 wire, with a velocity of about i cm. per second. The 

 negative electrons travel in the opposite direction with the 

 same charge, but with a smaller velocity. The masses are in 

 the ratio of about 9:1. Now according to Lang, the negative 

 electrons revolve round the heavier positive electrons in a 

 magnetised metal, like a planet round the sun, and the electric 

 convection currents thus produced are nothing more or less but 

 Ampere's "elementary molecular currents." Lang calculates 

 the speed of the electrons and the diameter of their orbit. The 

 speed is that of light, and the figures obtained lead to conclusions 

 in close agreement with known facts. 



An interesting article, entitled " Cartographie de laCaverne 

 Mammoth," is contributed by Dr. H. C Hovey to the Bulletin 

 de la Sociite de Spdleologie, tome v. 1899. The author gives a 

 short history of the attempts to map the celebrated Mammoth 

 Cave, and points out that, owing to objections on the part of the 

 proprietors, the scientific investigation of these caverns is still 

 incomplete. The paper is accompanied by reproductions of the 

 map by Hovey and Call, and that by C. R. Blackall for 

 purposes of comparison. 



A VALUABLE addition to our knowledge of the cretaceous 

 geology of Saxony is furnished by Dr. W. Petrascheck in a paper 

 published in the Abhandl. der Nahtrwiss. Gesellsch. Isis 

 (Dresden, 1900). The author seeks to trace the change of facies 

 developed at various horizons in the cretaceous rocks of this area 

 when followed laterally. He explains, as far as possible, the 

 modifications in the character of the fossil fauna which accom- 

 pany the changes in petrographical facies. The region dis- 

 cussed comprises the neighbourhood of Dresden and the well 

 known " Saxon Switzerland." 



The August number of iht Journal oi the Chemical Society 

 contains the Friedel Memorial Lecture, delivered before the 

 Society by Prof. J. M. Crafts. 



The second English edition of Prof. Ostwald's "Scientific 

 Foundations of Analytical Chemistry," translated from the 

 second German edition by Dr. George M'Gowan, has been 

 published by Messrs. Macmillan and Co. Since the original 

 work was published in 1894, the principles expounded in it have 

 been steadily gaining acceptance, but, so far as we are aware, no 

 English text-bcok of chemical analysis has appeared in which 

 he analytical methods and reactions of the laboratory are con- 

 istently explained in terms of the theory of ions instead of 

 NO. 1607, VOL. 62] 



being represented by the ideal equation- formulae. As Prof. 

 Ostwald states, the general standpoint of analytical chemistry 

 has undergone but little change ; nevertheless, the newer ideas 

 are gradually being applied to laboratory work by lecturers and 

 demonstrators who are in touch with modern chemical theory. 

 The new edition just published will be the means of extending 

 the knowledge of the fundamental principles underlying chemical 

 processes, and will be a source of inspiration to teachers who 

 wish to make analytical chemistry a science as well as an art. 



A SIMPLE method of preparing free hydroxylamine is given in 

 a recent number of the Annalen (311, 117) by Dr. R 

 Uhlenhuth. When the phosphate of the base is heated gently 

 under reduced pressure, the base distils over in a state of such 

 purity that the distillate solidifies on placing the receiver into 

 melting ice. 



Though the need for a universal standard table of atomic 

 weights is recognised by all chemists, the question whether it 

 shall be constructed upon a basis of O = 16 or H = i has 

 yet to be decided. The Chemical News publishes a letter 

 from Profs. Bredt, Erdmann, Fischer, Volhard, Winkler and 

 Wislicenus, members of the International Committee on Atomic 

 Weights, upon this point. It is remarked that if cogent reasons 

 necessitate an alteration of the standard of atomic weights, it 

 would be better to si art from an element of which the weight can 

 be conveniently ascertained, such an element, for example, as silver 

 or iodine, which also serves as a practical starting- point in con- 

 sideration of the sharpness of its reactions in numerous analytical 

 operations. But in the opinion of the writers such cogent reasons 

 for an alteration do not present themselves, for the ratio of 

 hydrogen to oxygen has been established with an exactness 

 which fully suffices for all practical purposes. It is felt that the 

 time for an unchangeable table of atomic weights has not yet 

 come ; for each succeed ing year brings corrections in the atomic 

 weights of the rarer elements, and at the same time speculations 

 as to their simple or compound nature. Opinions are therefore 

 invited upon the following questions: — (i) Shall the unity of 

 hydrogen be retained as the standard for reckoning atomic 

 weights? (2) Shall the atomic weights be given approximately 

 with two decimal places in which the uncertain figures can be 

 recognised by the type? (3) Shall the International Atomic 

 Weight Commission have the current table of atomic weights 

 edited on this basis ? Communications should be sent to Herr 

 Prof J. Volhard, Miihlpforte i, Halle-a-S. 



The additions to the Zoological Society's Gardens during the 

 past week include a Lioness (Felis led) from" South Africa, pre- 

 sented by the Right Hon. Cecil J. Rhodes ; a Black-backed Jackal 

 [Cam's mesomelas), a Leopard Tortoise (Testudo pardalis), a Puff 

 Adder [Bitis arietans) from South Africa, presented by Mr. 

 J. E. Matcham ; a Grey Ichneumon {Herpesles grisetis) from 

 India, presented by Mr. W. A. Gillett ; a Blue and Yellow 

 Macaw (Ara ararauna), a Red and Yellow Macaw {Ara 

 chloroptera) from South America, presented by Captain G. K. 

 Arnot ; a Chinese Quail (Co/«r«?jr chinensis) from China, two 

 Asiatic Quails (Perdicula asiaiica) from India, two Sparrow 

 Hawks {Accipiter nisiis), British, presented by Mr. D. Seth- 

 Smith ; a Common Quail (Cottirnix communis), British, pre- 

 sented by Miss F. E. Burt ; a Lesser W^hite-nosed Monkey 

 [Cercopithecus petaurista) from West Africa, a Polar Bear ( 6^5?*^ 

 maritimzis, ? ) from the Polar R.egions, two Black -headed 

 Caiques {Caica melanocephala) from Demerara, a Smooth- 

 headed Capuchin {Cehus monachus) from South-east Brazil, a 

 Pleurodele Newt [Molge walti), a Leopardine Snake (Coluber 

 leopardinus), a Vivacious Snake ( Tarbophisfallax), six European 

 Pond Tortoises [Emys orbicularis). South European ; two 

 Egyptian l.idisngaxQS (Urowasiix spinipes), an Algerian Tortoise 

 {Tesiudo ibera) from North Africa, four Alligator Terrapins 



