JOURNAL OF BACTERIOLOGY 



A SIMPLE ELECTROMETRIC OUTFIT 



FOR THE MEASUREMENT OF H-ION CONCENTRATION IN SOLUTIONS 



Operating on the compensation principle 

 but without a potentiometer 



No. 4886. Hydrogen-ion Outfit, with diagrammatic illustration of connections. 



A millivoltmeter system — operating on the compensation principle but mthout a potentiometer — 

 for the measurement of H-ion concentrations in solutions and, with the substitution of a plain plati- 

 num or other unattackable electrode in place of the hydrogen electrode, for the measurement of 

 o.xidation and reduction reactions. For the location of endpoints or variations in H-ion concen- 

 tration, the salt bridge shown in the illustration can be omitted. 



The arrangement is that of Hildebrand (see Journal of the American Chemical Society, 35: S47 , 

 1913) with a L. & N. d'Arsonval Galvanometer of the pointer type substituted for the capillary 

 electrometer. A stirring device of some convenient form (not shown in illustration) should be 

 used with the outfit. 



T he components of the outfit, which are sold separately under their respective catalogue numbers 

 are as follows: — 



4852. Hildebrand Hydrogen Electrode $5.75 



4834. Calomel Electrode Vessel 4.00 



4044. Single Contact Key 3.00 



4800. Portable d'Arsonval Galvanometer, 



I.. & N 18.00 



8714. Rheostat, 920 ohms 8.00 



9810. Weston D. C. Millivoltmeter, 0-1200 



millivolts 18.75 



8741. Coil, 10,000 ohms, mounted 10.00 



9373. Single Pole Single Throw Switch 65 



2410. Paired Burettes, ,^0 ml in 1/lOths, for 



titrating , $9.00 



9336. Support, large _ , 1.00 



3222, Clamps, (3) ea. .40 



2090. Burgess Super-sijc Dry Cells (2) ea. 1.00 



9357. Support 1.50 



3218. Clamp 70 



2128. Beakers, Pyrex Glass, 300 ml (2)....ea. .26 



4876. Bent Glass Tube is 



4886. Complete Outfit, as above listed $84.25 



Code Word Ezkci 



Prices subject to change without notice 



ARTHUR H. THOMAS COMPANY 



WHOLESALE, RETAIL AND EXPORT MERCHANTS 



LABORATORY APPARATUS AND REAGENTS 



WEST WASHINGTON SQUARE PHILADELPHIA, U. S. A. 



CABLE ADDRESS. "BALANCE." PHILADELPHIA 



