484 



SCIENCE 



[N. S. Vol. XXXII. No. 823 



The Rapid Determination of Silver, Copper, Cad- 

 mium and Bismuth by Means of the Meroury 

 Cathode and Stationary Anode: R. C. Benneb. 

 Work which has been recently completed indi- 

 cates that the rapid electrolytic determination of 

 many metals can be accomplished by means of 

 stationary electrodes in nearly the same time as 

 with the more complex forms of apparatus. 



In order to avoid loss by boiling of the solution 

 when high currents are used, tall electrodes sim- 

 ilar to those utilized by Smith were constructed. 

 Standard solutions of copper nitrate, silver ni- 

 trate, cadmium sulphate and bismuth nitrate 

 were prepared from chemically pure materials. 

 The electrolysis was carried out in case of each 

 metal in the presence of nitric acid, and sul- 

 phuric acid, with a current varying from three 

 to four ampei'es. The solution always had a 

 volume of twenty cubic centimeters. The results 

 were as accurate as could be desired and as good 

 as those obtained by Smith by means of the ro- 

 tating anode and mercury cathode. It is possible 

 to precipitate 0.3833 gram of copper in twenty 

 minutes, 0.2856 gram of silver in ten minutes, 

 0.743 gram of cadmium in ten minutes and 0.4G.50 

 gram of bismuth in twenty-five minutes. 

 The Atomic Weight of Tantalum: Claeence W. 

 Balke. 



Tantalum oxide was prepared from purified 

 potassium fluotantalate. It was converted into 

 tantalum pentachloride. The latter, weighed in 

 quartz bulbs with great care to avoid contact with 

 moist air, was hydrolyzed in portions weighing 

 from six to eighteen grams and the weight of 

 tantaliun oxide determined. Eight determinations 

 gave values for the atomic weight of tantalum 

 from 181.46 to 181.55 with a mean of 181.52, 

 which is one half of a unit higher than the value 

 given in the International Table of Atomic 

 Weights. 



Apparatus for the Determination of Arsenic: 

 Otis D. Swett. 



This is a self-contained apparatus, disposed 

 vertically within the limits of its base, which has 

 a diameter of 11 cm., and having a height of 

 44 cm. The reaction chamber is surrounded by a 

 jacket through which hot or cold water may be 

 passed as a temperature control. The charge is 

 admitted through a tube, sealed into a stopper 

 ground into the neck of the reaction chamber, 

 and extending to near the bottom of the latter, 

 where it terminates in a gas trap bend. The 

 arsine enters a tube, sealed into the said stopper, 

 passes through a drying tube, and into a combus- 



tion tube, fitted by means of a flat connection 

 with spring clip to the exit from the drying tube, 

 and heated electrically. Arsenic mirrors are 

 formed and compared with standards. The com- 

 bustion tube may be replaced by a suitably bent 

 tube with a horizontal limb carrying a sensitized 

 paper. 

 Potassium Ammonoplumiite and Potassium Am- 



monocadmiate : Edwaed C. Feankxin and 



Geoege S. Bohaet. 



Franklin and his coworkers have shown that 

 liquid ammonia is an electrolytic solvent which 

 exhibits many striking similarities to the more 

 familiar solvent water. In particular they have 

 shown that just as the ordinary oxygen or 

 " hydro " acids, bases and salts may be said to 

 constitute a water system, so there exists a large 

 number of nitrogen compounds which similarly 

 constitute an ammonia system of acids, bases and 

 salts. 



The authors now show that just as potassium 

 hydroxide, a water or hydrobase, in aqueous solu- 

 tion, reacts with lead hydroxide, an amphoteric 

 hydroxide, to form the hydrosalt, potassium 

 plumbite, in accordance with the equation, 



2KOH + Pb(OH)3 = Pb(OK), + HA 

 so potassium amide, an ammonobase, in solution 

 in liquid ammonia, acts upon lead imide, an 

 amphoteric imide, to form the ammonosalt, potas- 

 sium ammonoplumbite in accordance with the 

 equation, 



KNH, + PbNH = PbNK + NH,. 



The salt separates from concentrated solutions in 

 the form of beautiful, colorless, transparent crys- 

 tals of the formula, PbNK.3NH3. 



A potassium ammonocadmiate of the formula, 

 Cd(NHK)..2NH3, has been prepared by the action 

 of an excess of a solution of potassium amide on 

 cadmium iodide suspended in liquid ammonia. 

 Cuprous Nitrate: Wm. H. Sloan. 



When metallic copper is digested with a solu- 

 tion of eupric nitrate in liquid ammonia and 

 cuprous nitrate is formed and may be isolated in 

 tlie form of colorless crystals by the evaporation 

 of the solvent. The composition of the crystalline 

 salt is represented by the formula, CuN03-4NH3. 

 The Viscosity of Ammonia, Methylamine and 

 Sulphur Dioxide and Certain of their Solu- 

 tions: F. F. Fitzgerald. 



In agreement with the hypothesis that the more 

 fluid electrolytic solvents give solutions which 

 exhibit high maximum molecular conductivities 



