316 Scientific Intelligence. 



400 cc water and 20 grams of concentrated sulphuric acid in a 

 flask connected with a vertical cooler. After 11 or 12 hours 

 boiling, the solution was saturated with calcium carbonate, filtered 

 and evaporated to a syrup, then dissolved in strong alcohol, 

 again filtered and evaporated, and treated with absolute alco- 

 hol. The evaporated syrup from this solidified to a crystalline 

 mass after a lew days. Repeated recrystallization and a treat- 

 ment with animal charcoal gave a pure white crystallized sugar, 

 fusing at 144° to 145° and giving on analysis the formula C n H 2D O n . 

 It is dextrorotatory, [<*] D = + 18° or 19° for a solution which 

 had been made some hours. But it shows the so-called bi-rota- 

 tion markedly, the rotation five minutes after solution being 

 [af] D = + 85-86° or four and a half times that of a solution after 

 16 hours. From the curve of change it appears that the bi-rota- 

 tion at the instant of solution must be +100°. In its reactions 

 xylose resembles arabinose ; both yield with mineral acids furfurol 

 and not lsevulinic acid, as do the carbohydrates ; and on oxida- 

 tion, no mucic nor saccharic acid is formed. Treated with phlor- 

 oglucin and hydrochloric acid, both yield a cherry-red color, the 

 phenyl-osazones of both fusing at 160°. By Raoult's method 

 xylose was proved to be a penta-glycose C 5 H :0 O 5 an isomer of 

 arabinose. It yields trioxyglutaric acid and tri-oxybutyric acids 

 on oxidation while arabinose yields tri-oxybutyric acid only. — 

 Liebig's Annalen, ccliv, 304; Ber. Berl. Chem. Ges., xxiii, 15 

 (Ref.j, Jan., 1890. g. f. b. 



6. Qn the Identity of Cerebrose with Galactose. — Thierfelder 

 has examined the sugar obtained from the brain by Thudichum 

 and called cerebrose. It was prepared by the action of dilute 

 sulphuric acid on cerebrin. Since it reduces Fehling's solution, 

 yields mucic acid when oxidized with nitric acid, and resembles 

 galactose in its melting point, specific rotation, fermentation, and 

 phenyl-hydrazine compound, the author regards it as identical 

 with this sugar. — J. Chem. iSoc, lvii, 57; lviii,.121, February, 

 1890. G. F. B. 



7. Dust in the Atmosphere. — At a meeting of the Royal So- 

 ciety, January 27, Mr. John Aitkin expressed his belief that 

 " dust condenses moisture before the air is saturated. For the 

 same number of dust particles per cubic centimeter, the atmospheric 

 transparency depends upon the depression of the wet bulb, being 

 large when the depression is large, but becoming small before the 

 depression vanishes. Increase of temperature also reduces trans- 

 parency when the number of particles remains the same, for in- 

 crease of temperature means increase of vapor pressure. «As a 

 rule, quantity of dust decreases when the wind increases. When 

 calms occur dust accumulates. This increases the radiating power 

 of the air, so that it cools quickly and fog forms. Thus a log may 

 be regarded as a suspended dew." — Nature, Feb. 20, 1890, p. 

 382. j. t. 



8. The Sun's Heat. — K. Angstrom, in his carefully prepared 

 papers, gives the result of his investigations upon the effect par- 



