SCIENCE.— AD VERTISEMENTS. 



Scientific Apparatus 



"Bowdoin" X-Ray Focus Tube. 

 My Specialties Are : 



"W-S" X-Eay Apparatus ; AVeston Ammeters, Volt- 

 meters and Wattmeters ; ' ' Chlorid Accumulator ' ' Stor- 

 age Batteries ; Electrical pleasuring Instruments ; Phys- 

 ical and Optical Apparatus ; Pyschological Apparatus, 

 etc. 



" Duty Free" Importations from all prominent 

 European makers. 



Correspondence requested. 



JAMES Q. BIDDLE, 



Dealer, Manufacturer's Agent and Importer, 



909 Drexel Building, PHILADELPHIA. 



Dec. I, 1896. Just Published. Sixth Edition of 



THE MICROSCOPE '^H^'^i^^SSi}- 



By SIMON HENRY GAGE, Professor of Microscopy, His- 

 tology and Embryology in Cornell University and the 

 New York State Veterinary College, Ithaca, N. Y., U.S A. 

 Sixth edition, rewritten, greatly enlarged, and illustrated 

 by 165 figures in the text. Price, $1.50, postpaid. 



COMSTOCK PUBLISHING CO., Ithaca, N. Y. 



Pomhi*ion Fnceile ^ ^''''Se collection of Upper 

 bamuridn rU&bllb. Mississippi Cambrian fossils 

 from the St. Croix (Potsdam) sandstone for sale. Mostly 

 Trilobites. Send for low prices. 



W. A. FINKELIMBURG, WlNONA, MiNN. 



NEW CATALOGUE. 



We have recently issued a new edition, revised and en- 

 larged to 6i pages, of our catalogue of 



Books on Chemistry, Cliemical 

 Teclinolog;^ and Physics. 



It is arranged by subjects, and includes all the standard 

 books in Chemical and Physical Science, as well as the re- 

 cent literature up to date. 



A copy of this Catalogue will be sent free by mail to any 

 address. 



D. Van Nostrand Company, 



Publishers and Importers of Scientific Books, 

 23 Murray St. and 27 Warren St., New York. 



Deliciom 

 t>rn}k 



Horsford's Acid Phosphate 



with water and sugar only, makes a 

 delicious, healthful and invigorating 

 drink. 



Allays the thirst, aids digestion, and 

 relieves the lassitude so common in 

 midsummer. 



Dr. M. H. Henry, New York, says : "When 

 completely tired out by prolonged wakefulness 

 and overwork, it is of the greatest value to me. 

 As a beverage it possesses charnns beyond any- 

 thing I know of in the form of medicine. 



Descriptive pamphlet free. 



Rumford Chemical Works, Providence, R. I. 



Beware of Substitutes and Imitations. 



RARE MINERALS. 



THAUMASITE, from Paterson, N. J., a sulphate, silicate and 

 carbonate of calcium, pure white, 2Sc. 



EKDEMITE, bright yellow on red wulfenite, Arizona, 50c^ 



-inch crsytallized balls,. 



Collections for Schools. 



ALPHA COLLECTION, twenty-five specimens in trays, con- 

 tained in a neat wooden box and accovipanied by a i6- 

 page guide book (XIII., Guide for Science Teaching, Bos- 

 ton Society of Natural History), Price, complete, $1.00. 



CABINET COLLECTIONS, 100 specimens, small size, $5.00. 

 100 specimens, large size, $10.00. These specimens are 

 each accompanied by a label giving name, system of 

 crystallization, chemical formula, and locality, and make 

 a good working collection for a student. 



EXCELSIOR COLLECTION for high schools and colleges. 

 200 specimens, nicely mounted on wooden blocks, with 

 beveled fronts for receiving labels. Price, packed, 

 $100.00. /School Bulletin ^Kist o\A. 



Loose Crystals. 



Small packages of free crystals for crystallographic study 

 may be sent for inspection by mail at small cost. Ap- 

 proval boxes of cabinet specimens by express or freight. 



ROY HOPPING, 



MINERAL DEALER, 



NEW YORK. 



504=506 Liberty Building, 



Liberty and Greenwich Sts. 



