SCIENCE-ADVERTISEMENTS 



DIONIC WATER TESTER 



Substitutes an extremely simple measurement of electrical con- 

 ductivity for the chemical reactions hitherto employed. Entire 

 test takes less than a minute to perform. By the use of this ap- 

 paratus, any unskilled person can detect and measure traces of im- 

 purities so small as to escape chemical analysis. It has been found 



for measuring slight traces of 

 impurities in distilled water, 

 sewage pollution in rivers, the 

 rj^hardness of water, etc. "When 

 it is desired to know how 

 much of a known substance is 

 present in the water, the 

 Dionic Tester gives the answer 

 with a rapidity and simplicity 

 unapproached by any other 

 method. 



Write for descriptive catalog to 



2111-13 ARCH ST. 



JAMES G. BIDDLE 



PHILADELPHIA, PA. 



When in Fbiladelphia be sure to Tisit our Permanent Erhitit of Scientific Instrnments. 



Moscow Natural Eye Model 



Pat Feb 3, 1914. 



A New and Valuable Aid in Teachinff Anatomy and 

 Physioloffy of the Eye 



These models consist of a real, natural eye 

 which hag been hardened and fixed: then sectioned 

 In half and mounted in a glaas cell eo as to show all 

 the internal parts of the eye ball. These structures 

 are all held in their normal positions, and may be 

 easily dentlfied by means of the diagrammatic cut, 

 keyed to model, which accompanies each one. 



"Ihe Moscow Natural Eye Models are excellent 



fireparations. We find them to be a great hel p in 

 aboratiry work, in Zoology, Physiology, Anatomy, 

 etc., etc ," Dr. J. E. Wodsedalek, Professor of Zoology, 

 University of Idaho. 



Mounted in ebonized box with hinged coTcr, 

 which protects the gjass cell from injury. Absolute- 

 ly permanent, and fully guaranteed. 

 Send for descriptive literature. 

 Manufactured by 



MOSCOW OPTICAL COIMPANY 



MOSCOW, IDAHO. 



Reichert Microscopes 



TOR AI.I, SCIENTIFIC SESEARCBSS 



(Medicins. Botany, Mineralogy, Metallurgy, etc.) 



Microtomes 



Haemoglobinometers 



Mirror Condensers 



FOR ULTRAniCROSCOPICAI. WORK. 



Apparatus for 



PHOTO-niCROGRAPHY 



and PROJECTION 



CATAI,OGU:SS FREE ON DEStANU 



C. REICHERT %l^^l VIENNA 8/2. 



