Chemistry and Physics. 393 



ether to a stiff magma. — Ber. Berl. Chem. Ges., xxxi, 2993-7, 

 December, 1 898. G. f. b. 



2. On Reductions in Presence of Palladium. — Although pal- 

 ladium-hydrogen has been used already as a reducing agent by 

 Graham and by Saytzeff, yet now by a more extended study 

 Zeltnsky finds that it may be employed with great success in 

 the reduction of bromides and iodides of cyclic alcohols, a class 

 of compounds which hitherto it has been impossible to reduce by 

 any of the ordinary methods. The form in which it is used is 

 that of a palladium-zinc couple, analogous to the copper-zinc 

 couple of Gladstone and Tribe. To form it, zinc filings are well 

 washed with alcohol, then treated with sulphuric acid until an 

 active evolution of gas takes place, and finally washed with 

 water. On pouring upon them a one or two per cent solution of 

 palladium chloride previously acidified with hydrochloric acid, a 

 thin strongly adhering layer of palladium is deposited upon the 

 zinc. The couple thus formed is washed with alcohol and dried. 

 To effect the reduction, which takes place at the ordinary temper- 

 ature and up to 100°, a flask provided with a reflux-condenser and 

 dropping funnel is one-third filled with the palladium-zinc couple, 

 this couple is partly covered with methyl or ethyl alcohol and hy- 

 drochloric acid saturated at 0° is run in drop by drop. At first the 

 hydrogen is absorbed by the palladium ; and as soon as bubbles 

 of gas are evolved, the bromide or iodide to be reduced is added 

 gradually, alternately with the acid. The action is controlled by 

 regulating the quantities of material added. The evolved gases 

 are passed through alcohol to retain any volatile hydrocarbon 

 which may be carried over. The palladium-zinc in the flask, after 

 washing with acid and with alcohol, is ready for further use. — 

 Ber. Berl. Chem. Ges.,xxxi, 3203-5, January, 1899. g. f. b. 



3. On the Properties of Metallic Calcium. — Further results 

 have been communicated by Moissan on the properties of calcium. 

 Prepared by the method already described,* the metal separates 

 from fused sodium in hexagonal crystals which have a specific 

 gravity of 1*85 and melt at 760° in vacuo. On solidifying, the 

 metal is somewhat brittle, is less malleable than potassium or 

 sodium and shows a crystalline fracture. When free from nitride, 

 it is silver-white in color and has a brilliant surface. Heated to 

 redness in a current of hydrogen, a crystalline hydride CaH 2 is 

 formed. When pure, calcium is not acted on at ordinary tem- 

 peratures by chlorine ; though at 400° the action is decided. But 

 if the metal contains nitride, chlorine attacks it at the ordinary 

 temperature. At 300° it ignites and burns brilliantly in oxygen. 

 Gently warmed in air, it burns with brilliant scintillations. It 

 combines with sulphur at 400° with incandescence. At a red 

 heat it unites actively with lamp-black, yielding CaC 2 . Calcium 

 gives somewhat brittle alloys with magnesium, zinc and nickel. 

 With tin the alloy contains 3 '82 per cent of calcium, has a density 

 of 6*70, and slowly decomposes water. A crystalline amalgam is 



*This Journal, IV, vi, 428, November, 1898. 



