SCIENCE— ADVERTISEMENTS 



* 



Leitz Microscopes are the 

 Standard of the World 



LEITZ LABORATORY AND STUDENT 

 MICROSCOPES "L" AND "LL" 



A Student Microscope is naturally subjected to hard usage 

 and in order to withstand severe handling, its workmanship 

 has to be durable beyond question. 



The Leitz Laboratory and Student Microscopes embody the 

 same high standard of optical and mechanical workmanship, 

 so strongly identified with Leitz products, and are guaranteed, 

 therefore, to serve in student laboratories in a more satisfactory 

 manner than any others. 



The "Leitz-Quality" is b»yond comparison, and since it 

 is unequalled, it is supreme. 



Optical and Mechanical Efficiency are the chief points ex- 

 pected of any microscope ; the Leitz instruments are recog- 

 nized to possess these standards to a non-con testable degree. 



Write for Pamphlet No. O-lOOl 



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 VWORHMANSHI^^/ \ llCTf tVJIAIX/ \ "■■ SUPREME / 



60 East 10^-=5t 



NEW 

 Spencer Refractometer 



Of the well known Abbe type with water jack- 

 et for controlling temperature of the prism case, 

 designed for obtaining the data on all transparent 

 substances (except gases) whose indices (Nq) fall 

 between 1.30 and 1.71 



Several new and improved features of con- 

 struction, incorporated. 



Complete outfit 

 including thermo- 

 meter 



$200.00 



Send for booklet S No. 1 which ako includes 

 Spectrometers, Spectroscopes, Goniometers, etc. 



SPENCER LENS COMPANY 



Buffalo, N. Y. 



