434 Scientific Intelligence. 



f J. Carl Wilhelm Scheele — Briefe und Aufzeichnungen heraus- 

 gegeben von A. E. Nokdexskiold. Roy. Svo, 491 pp. Stockholm, 

 1892. — In thus preserving in permanent form and making public 

 the scientific letters and laboratory notes of Scheele, Professor 

 Nordenskiold has rendered a great and lasting service to the his- 

 torical literature of science. There seems to be a period of retro- 

 spection in chemistry at present and a desire to place its historical 

 foundations on a sure basis, and thus the appearance of this pub- 

 lication is particularly opportune. 



Among the crowd of eager and gifted searchers of the last half 

 of the previous century, with whom the modern era of chemical 

 science began, no figure stands out more luminous or conspic- 

 uous than that of Scheele. When we consider the particularly 

 unfavorable conditions under which he worked, compared with 

 the magnitude of the results he achieved, by the force of skill, 

 energy and intellect, he must at once take place in the front rank 

 of scientists of all ages. His claim to this position is materially 

 strengthened by this publication of his notes and letters. To him 

 must be ascribed the prior discovery of oxygen, chlorine, man- 

 ganese, baryta, and many other discoveries which would have 

 entitled a chemist to renown. Of particular importance were his 

 researches in the line of organic chemistry, which are now for 

 the first time fully set forth. 



It is certainly true, as Professor Nordenskiold remarks, that these 

 letters will be read with interest and pleasure by every chemist 

 and thinker, engaged in original research. They are chiefly ad- 

 dressed to Scheele's friends, Retzius, Gahn and Bergmann. Besides 

 the notes and letters which have been carefully turned into mod- 

 ern German and are accompanied by critical notes, there is an 

 able sketch of Scheele's life and facsimiles of his writings. The 

 volume is moreover a beautiful specimen of the typographical 

 art. l. v. p. 



8. Simple apparatus for measuring the Index of refraction of 

 Liquids. — H. Ruoss immerses a mirror vertically in the liquid, 

 leaving a portion not immersed. The mirror can be turned about 

 a vertical axis. At a suitable distance, about four meters, is placed 

 a scale and telescope. The reflection of the scale in the air and 

 in the liquid are then observed. One can make many observa- 

 tions at different angles of refraction by turning the mirror. 

 The mean error of a single determination of index of reflection of 

 water at 22-9° C. with sodium light was 0*00011 to 0*00005. — 

 Ann. der Physilc und Chemie, No. 3, 1893, pp. 531-535. j. t. 



9. Electromagnetic Theory of Color dispersion. — H. yon 

 Helmholtz points out that no satisfactory explanation of color 

 dispersion by the electromagnetic theory has been given. He 

 accordingly submits the question to mathematical analysis, com- 

 bining his own theories of electrically charged molecules with the 

 general equations of Maxwell, and is led to a satisfactory explan- 

 ation of the subject by means of the electromagnetic theory of 

 light. — Ann. der Physik und Chemie, No. 3, 1893, pp. 389-405. 



J. T. 



