Febeuaet 19, 1909] 



SCIENCE 



317 



purchase in such a case of glass parts only. (5) 

 Electrical connection is made through a length of 

 copper wire. Good contact may then be got by 

 means of screw connectors. 



The Rapid Precipitation of Metals on Gauee 

 Cathodes with Fixed Electrodes: John T. Stod- 

 dard . 



Cadmium, copper, nickel, silver, zinc and prob- 

 ably other metals may be quantitatively precipi- 

 tated for their solutions upon a fixed gauze 

 cathode, with a fixed anode in about the same 

 time as that required when rotating electrodes 

 are employed. The current used is about the 

 same as in the latter method. 



The cylindrical cathode, 3 cm. in diameter and 

 3 cm. high, is made of platinum gauze, described 

 by the maker as 52-mesh and made of 0.004 inch 

 wire. Its total surface is calculated to be about 

 40 sq. cm. The anode is a cylinder of platinum 

 foil, about 2.5 cm. high and of a diameter which 

 may vary between 0.5 and 1.2 cm. 



It is placed concentrically within the gauze 

 cathode. The electrolysis is carried out in a 

 80 c.c. beaker with about 50 e.c. of solution, in 

 order to gain the advantage of concentration. 

 The current strength may vary within wide limits 

 in most cases without influencing the character 

 of the deposits, but the time is greatly shortened 

 only when comparatively high currents are used. 

 It appears that the more or less troublesome 

 and expensive arrangements for rotating one of 

 the electrodes, or of agitating or rotating the solu- 

 tion by mechanical means or by the use of a mag- 

 netic field are quite unnecessary for rapid and 

 complete precipitation. 



The character of the deposited metals is excel- 

 lent, and entirely satisfactory analyses have been 

 made by the method described above. 



The Rapid Precipitation of Metals in a Mercury 

 Cathode with Fixed Anode: John T. Stoddabd. 

 Cadmium, copper, nickel, silver, zinc and prob- 

 ably other metals can be precipitated in a mer- 

 cury cathode with a fixed anode in substantially 

 the same time as that required with the use of a 

 rotating anode. The anode is a flat spiral of 

 platinum wire, and it is placed 1.05 cm. from 

 and parallel to the surface of the mercury in a 

 50 c.c. beaker. The cathode connection is made 

 by a platinum wire, which is protected from the 

 solution by a small glass tube sealed to it 2-3 pim. 

 from the end, which dips into the mercury. 



The solution may have any volume from 10 c.c. 

 to 30 c.c. The strength of current is limited only 

 by the danger of loss from too violent boiling of 



the solution. About 40 g. of mercury are used 

 as cathode. 



The following table shows the time necessary 

 for complete precipitation of the metals: 



Approx. Current Time iu 



Metal Amount Strength Minutes 



Cadmium 0.21 g. 5 Amp. 10 



Copper 0.4 4 8 



Nickel 0.2 6 12 



Nickel 0.5 7 15 



Silver 0.5 8 7 



Zinc 0.4 6 15 



Analyses made by this method give satisfactory 

 results, concordant with those made from the 

 same solutions with gauze cathode and fixed 

 anode. 



Some Neio Laloratoj-y Apparatus: John T. Stod- 

 dard. 



1. The wire- test-tube holder, described by the 

 writer in the Journal of Analytical Chemistry, 

 January, 1890, is used as the clamp on a light 

 stand. The clamp is adjustable at any angle and 

 up to lOi inches in height above the table. The 

 support is well adapted to many services in the 

 laboratory and has great stability from the special 

 design of its base. 



2. A funnel support which fits on the above 

 stand consists of circular plate of aluminiiun 

 with openings for the reception of four funnels. 

 The special base of the stand insures stability for 

 a much greater load than the funnels when full 

 of solution. Its chief advantage is compactness. 



3. A wire dish holder, which grasps an evapo- 

 rating dish by the edge and holds it securely. 



Abstracts have not been received for the follow- 

 ing papers: 



A Neto Method of Determining the Partial Vapor 

 Pressures of Binary Mixtures: M. A. Rosanoff 

 and Aethub B. Lamb. 



On the Partial Vapor Pressures of Binary Mix- 

 tures: M. A. RosANOPF and 0. W. Easley. 



Recent Evidence for the Existence of Hydrates in 

 Aqueous Solutions: H. C. Jones. 



A New Law concerning the Vapor Pressures of 

 Binary Mixtures: M. A. Rosanoff. 



On the Duhem-Margules Equation as applied to 

 Binary and Ternary Mixtures: William Ed- 

 WAED Stoky. 



Preparation of Pure Hydrogen and the Elimina- 

 tion of Oxygen: Geo. A. Hulett. 



A Maximum Volt Meter: W. Lash Miixee. 



The Relations between Viscosity and Fluidity: 

 Eugene C. Bingham. 



