156 Scientific Intelligence. 



ignited coke, neither absorption nor evolution of heat will take 

 place; producing a water generator gas, as in the Dowson 

 process. Or (2) by mixing the air with carbon dioxide before 

 passing it over the ignited coke; the reaction C0 2 + C=(CO) 2 

 being endothermic, 3S270 calories being absorbed, and the result- 

 ing product being a carbon-dioxide generator gas. The author 

 gives the composition of gases thus prepared, and compares them 

 together, with respect (A) to the heat of combustion of one liter 

 of the gas, calculated from composition, (B) to the calorific 

 intensity, so calculated, and (C) to the specific heat of the com- 

 bustion-products of the gas; i. e. the heat evolved by one liter of 

 these combustion products when cooled 1°. These results are as 

 follows : 



Gas. A. B. C. 



1. Generator gas :... 1044 cal. 3904° 0-5487 cal. 



2. Carbon-dioxide gas 1739 " 2449 0-7101 " 



3. Water generator gas (liquid water at' 15°) 1652 " 2356 07016 " 



4. " " •' (water-vapor at 15°) 1790 " 2431 0-7363 " 



5. Water gas 2812 " 2830 0-9934 " 



— Ber. Berl. Ghent. Ges., xxv, 556 ; J. C/iem. Soc, lxii, 673, June, 

 1892. G. E. B. 



2. On the Temperature of Ignition of Electrolytic Gas. — More 

 than a year ago Krause and V. Meyer showed that electrolytic 

 gas, slowly passed through a glass tube immersed in boiling stan- 

 nous chloride, at 606°, does not explode. Fkeyer and V. Meter 

 have now repeated this experiment using other liquids of higher 

 boiling points. The bath was of sheet iron, in the form of a cru- 

 cible, and was 10 cm. high and 6 cm. in diameter. Through the 

 cover passed a sheet-iron tube 2 cm. in diameter closed at its 

 lower end and extending nearly to the bottom of the vessel. Out- 

 side this tube was half a kilogram of zinc chloride. Within the 

 tube a cylindrical glass bulb was placed, connected by capillary 

 tubes with the gas-evolution apparatus and with a water trough. 

 The zinc chloride was heated to boiling, the temperature rising to 

 redness. On passing the electrolytic gas through the bulb, explo- 

 sion took place at once, and this, whether the gas was moist or 

 dry. By means of an air thermometer constructed of platinum, 

 the temperature of the boiling zinc chloride was fixed at 730°. 

 The experiment was then repeated with zinc bromide and it was 

 found that the explosion did not take place in actively boiling 

 zinc bromide, the boiling point of which was found to be 650°. 

 Hence the ignition point of e'ectrolytic gas lies between 650° and 

 730°. The authors observed that the explosion in the zinc chlo- 

 ride takes place with certainty only when the gas is introduced 

 into the chloride in active ebullition. If it be passed through be- 

 low the boiling point and then the temperature be raised to 730°, 

 a slow union takes place, forming water. — Ber. Berl. Chem. Ges., 

 xxv, 622; J. Chem. Soc, Ixii, 680, June, 1892. g. f. b. 



3. On the Electromotive Activity of the Ions. — In 1890, Nernst 

 and Planck deduced the electromotive forces between liquids 



