SCIENCE— ADVERTISEMENTS 



Are You Arranging For Your Physics 



Courses For Chemical and 



Medical Students ? 



May we help you f 



You realize, of course, the important bearing of electrical measuring 

 instruments upon many of their problems; 



With this realization, we have prepared a summary of the physico- 

 chemical and physical principles involved in measurements of acidity 

 and alkalinity of solutions — a subject of vital importance to the chemist 

 and biochemist. ■ This summary is just off the press, under the title : 

 " Electrometric Methods and Apparatus for Determining Hydrogen- 

 Ion Concentrations," and it constitutes Catalogue S75 of our series of 

 publications. 



The title suggests the subject matter, virhich is a concise summary 

 of the various electrometric methods by means of which the measure- 

 ments can be made. A review of the physico-chemical theory of the 

 measurements is a valuable part of the treatment. Practical hints on 

 the technique are given. A selected bibliography points the way to more 

 detailed information. A price list of typical equipments rounds out the 

 discussion. 



It is our belief that any Instructor in Physics who is planning 

 his " Applied Physics " courses for the coming year will irnd this treatise 

 of great assistance. A limited number of copies will be available for 

 distribution to his classes. 



Other bulletins of the same general nature will shortly be pub- 

 lished. Ask for your copy of Catalogue S75, and state whether you 

 wish to receive the future publications. It will be appreciated also if 

 you will state how many copies of each may be required for your classes. 



LEEDS 8c NORTHRUP COMPANY 



ELECTRICAL MEASURING INSTRUMENTS 



4901 STENTON AVENUE PHILADELPHIA, PA. 



