76 Scientific Intelligence. 



its density increasing gradually downward, the isolated portion 

 above mentioned will be in equilibrium in the liquid when it has 

 fallen through a distance dli; so that the positive work done in 

 this case will be an infinitesimal of the second order and therefore 

 negligible. From a formula deduced in the paper, the authors 

 have calculated the amount of substance at the top and at the 

 bottom of a column 100 meters high, for four different solutions. 

 For cadmium iodide at top 0-166, at bottom 0*153; a difference of 

 0-013. For sodium nitrate 0*20 and 0-196; a difference of 0-004. 

 For common salt 0-11 and 0*1095; a difference of 0*0005. And 

 for sugar 0*55 and 0*546; a difference of 0*004. These differences, 

 though apparently too small to have any practical value, have a 

 very considerable theoretical importance. — Ann. Chim. Phys. y 

 VI, xii, 384, Nov., 1887. g. r. b. 



4. On the Percentage of Oxygen in the Air. — Hempel has 

 published the results of analyses of the air of Dresden, made for 

 the most part by his assistants Oettel and Schumann, in compari- 

 son with analyses of air collected simultaneously at Poppelsclorf, 

 near Bonn, by Kreusler, at Cleveland by Morley, at Para, Brazil 

 (lat. l£° S.) by Pusinelli, and at Tromsoe, Norway (lat. 69^° N.) 

 by Schneider. The samples analysed were taken daily between 

 April 1 and May 16, 1886, the hour being 2:12 p. m. at Bonn, 

 and the corresponding time at the other stations. The results are 

 given in detail in tabulated form. They show that the mean per- 

 centage of oxygen in the air was for Para 20*92, Bonn 20*92, 

 Cleveland 20*93, Dresden 20*93, and Tromsoe 20*95. The highest 

 observed percentage was 21*00 at Tromsoe on April 22d; and the 

 lowest 20*86 at Para on April 26th. The mean percentage as de- 

 duced from all the experiments is 20*93. — Ber. Berl. Chem. Ges. y 

 xx, 1864, June, 1887; J. Chem. Soc, lii, 885, Oct., 1887. 



G. P. B. 



5. On the Constitution of Selenous Acid. — Michaelis and 

 Landmann have continued their researches on the constitution of 

 selenous acid and have offered new proof that this is a di-hydroxyl- 

 acid SeO . (HO) 2 . They have produced the chloride of eth- 

 oxyselenyl, C 2 H 6 . SeO . CI, by distilling selenyl chloride with 

 absolute alcohol for a long time with an inverted condenser. 

 They have also formed di-ethyl selenite (C 2 H 6 0) 2 SeO, either by 

 the action of selenyl chloride upon sodium ethylate or by that of 

 silver selenite on ethyl iodide. This ether has a density of 1*49 

 at 16*5° and boils between 183° and 185°. — Ber. Berl. Chem. Ges., 

 xx, (Ref.) 625, Nov., 1887. g. f. b. 



6. Bidexing of Chemical Literature. — The fifth annual report 

 of the Committee of the American Association for the Advance- 

 ment of Science on Indexing Chemical Literature has recently been 

 received. The report mentions the publication of Professor C. E. 

 Munroe's Index to the Literature of Explosives, Part I, in which no 

 less than 442 volumes of serials have been indexed. After noticing 

 reports of progress from eight persons, the report considers the 

 suggestion of the chairman made at the Buffalo meeting as to the 



