Mabch 15, 1907] 



SCIENCE. 



415 



ments of the equilibrium in the Deacon 

 process between 350° and 420°, and (3) 

 from the decomposition pressure of mer- 

 curic oxide. These methods give concor- 

 dant results which show that the E.M.F. 

 of the oxyhydrogen cell is about 1.224 volts, 

 a value which is higher by one tenth of a 

 volt than the one hitherto accepted. 



Calculation of Some Chemical Equilibria 

 hy the Nernst Formulas: K. G. Falk. 

 The equilibria for the reactions 



2S0a -1- O2 = 2SO3, EL + CI: : 

 H2 + Bri, = 2HBr 



:2HC1, 



are calculated for different temperatures 

 by means of the formulas developed by 

 Nernst, and which formed the subject of 

 the Silliman lectures (delivered by Nernst) 

 at Yale University in 1906. The calculated 

 values are compared with those found ex- 

 perimentally. 



Cadmium Sulphate and Mercurous Sul- 

 phate: G. A. HXILETT. 



The Quantitative Determination of Small 

 Quantities of Arsenic hy the Method of 

 Marsh-Liebig as affected by Superten- 

 sion and Potential Differences: Wm. D. 

 Haekins. 



The injurious action of iron and other 

 metals in hindering the reduction of arsenic 

 in the Marsh apparatus, can be prevented 

 by using a temperature of 100° or by the 

 addition of salts of tin, cadmium, lead or 

 bismuth, using the proper conditions. The 

 factors aiding in the reduction when a 

 foreign metal is present or added are: (1) 

 (most important) high superpotential ; (2) 

 distance from zinc in the scale of poten- 

 tials; (3) degree of solubility of the salts 

 formed. Two lengths of hard glass tube 

 should be heated in two fire-brick furnaces 

 to give complete decomposition of the 

 arsine. The method is quantitative. 



The Vapor Pressure of Aqueous Nitrate 

 Solutions by the Air-bubbling Method: 

 A. T. Lincoln. (By title.) 



Melting-point Determinations at Low Tem- 

 peratures: Leo F. Guttmann. 

 A constantan-copper couple connected in 

 series with a sensitive D'Arsonval galva- 

 nometer is used, and standardized by deter- 

 mining the known melting points of ice, 

 chloroform, paste of solid carbon dioxide 

 and alcohol, ether and the temperature of 

 liquid air. From the data thus obtained 

 a calibration curve is drawn up. To deter- 

 mine the melting point of a substance, the 

 couple is immersed in the liquid contained 

 in a glass tube, and the liquid frozen. By 

 allowing the substance to warm up slowly, 

 and watching the galvanometer deflections 

 the melting point is ascertained. The 

 melting points determined were those of 

 some of the alkyl alcohols, esters, and 

 iodides, the paraffins, aeetaldehyde, ethyl 

 methyl ketone, acetone, ethyl bromide and 

 chloride, toluene, ethylbenzene and the 

 xylenes. 



The System Sodium Chloride, Sodium Sul- 

 phate, Calcium Sulphate and Water: F. 

 K. Cameron, J. M. Bell and W. 0. 

 Robinson. 



The invariant points and boundaries for 

 the system sodium chloride, sodium sul- 

 phate, calcium sulphate, and water were 

 determined at 25° and the solid diagram 

 constructed. It was shown that fields 

 existed for solutions in contact with the 

 following solid phases: NaCl, NaaSO^* 

 10H,O, 2Na,,S0, -SCaSO^ (glauberite) and 

 CaSOi'HaO. No anhydrite field exists. 



The Colors of Colloidal Silver: Wilder D. 

 Bancroft. (By title.) 



Studies in Catalysis; Amidine Formation: 



Julius Stieglitz. 



The formation of amidines according to : 

 RC(:NH)OR' + NH3 = RC(:NH)NH2 



