SCIENCE— ADVERTISEMENTS 



"TURTOX 



Aquaria 



Bird glasses 



Charts 



Chemicals 



Dissecting outfits 



Earthworms (spe- 

 cial) 



Entomological sup 

 plies 



Glass\rare 



Lantern Slides 



Life Histories 



Microscopes 



Microscope slides, 

 (General) 



CATALOGS include 



Microscope slides, 

 (special for High 

 Schools) 



Microtomes 



Models 



Museum Prepara- 

 tions 



Preserved Material 

 for Botany, Em- 

 bryology and 

 Zoology 



Insect Mounts 



Skeletons 



Syringes, Injectinf; 



Vascula 



and many other itenu. 



Items in black type are our own special products. 



We are Manufacturers and Preparators ci 



Biological Supplies. 



UCTS 



all of the above iteau 



request. 



GENERAL BIOLOGICAL SUPPLY HOU^ 

 1177 EAST 55TH STREET, CHICAGO, ILL. 



WANTED, 



Formulae and Processes for Chemicals 

 used in the Pharmaceutical Trade. Ad- 

 dress: G, c|o Science, Garrison, N. Y. 



FOR SALE 

 Journal of the Washington Academy of 

 Sciences, Volumes 3 to 12 inclusive. 

 These ten volumes, complete, unbound, 

 are listed at $6.00 each. They are offered 

 here for $50.00. W. A. Orton, Depart- 

 ment of Agriculture, Washington, D. C. 



ELECTRICAL BV1EASUR3MG 

 INSTRUMENTS 



FOR PHYSICISTS AND 



PHYSICAL CHEIWISTS 



EQUIPMENTS SUITABLE FOR RESEARCH 

 AND INDUSTRIAL LABORATORIES 



We Solicit Inqtiiries 



LEEDS &, MORTHRUP CO. 



4901 STENTON AVENUE 



PHILADELPHIA 



Jagabi Rheostats 



meet a definite need in Educational, Re- 

 search and Industrial Laboratories. 

 By means of sliding-con- We find greatest demand 

 tacts the resistance values for Rlieostats witti tubes 

 can be varied from zero to .16" long, as illustrated 

 full rating, in exceedingly above. Write for "De- 

 sraall steps. scripiivc Bulletin S 9:^0. 



James G. Biddle. Philadei_phia 



1211-13 ARCH STREET 



REACTIONS OF SOILS 



May be quickly and accurately determined 

 through use of the 



"LAMOTTE" 

 INDICATOR FIELD SET 

 Complete with instructions. $4.25 (delivered) 

 H-Ion concentration of water and solutions 

 quickly and easilj' determined by the 



"LAMOTTE" 

 H ION COMPARATOR SET 



Complete and ready for use. $9.10 (delivered) 

 Send for Literature. 



LaMotte Chemical Products Co. 



Baltimore. Md., U. S. A. 



PRECISION 



Forks 



Made in wide range of frequency up to 5000 vibrations. Twenty-five years of experienca 

 have placed us in position to guarantee absolutely accurate rating. In rating our Forks we 

 use a standard supplied by Dr. D. C. Miller, of the Case School of Applied Science, Cleve- 

 land, Ohio. Our electrically maintained Forks are well known for their convenient mount- 

 ings permitting of great range of adaptability. 



WRI. GAERTNER & CO., 



5345-49 Lake Park Ave., Chicago, 111. 



