SCIENCE.— AD VERTISEMENTS. 



RARE MINERALS. 



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

 carbonate of calcium, pure white, 25c. 



EKDEMITE, bright yellow on red wulfenite, Arizona, SOc. 

 NATIVE ARSENIC, Japan, \i to J^-iuch crsytallized balls, 

 2Sc, 3SC. 



Collections for Schools. 



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

 tained in a neat wooden box and accompanied by a 1,6- 

 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. Hchool BulleUn just out. 



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, 



504=506 Liberty Building, 

 Liberty and Greenwich Sts. 



NEW YORK. 



Tlie Thomas A. Scott Fellowship in Hygiene, 

 University of Pennsylvania. 



The Scott Fellowship in Hygiene at the University of Penn- 

 sylvania falls vacant October 1st, 18'J7. Individuals desirous 

 of applying for appointment to the position can obtain de- 

 tails of the governing regulations by communicating with 

 Prof. A. C. Abbott, Director of the Laboratory of Hygiene, 

 University of Pennsylvania, Philadelphia. 



NEW CATALOGUE. 



We have recently issued a new edition, revised and 

 enlarged to 64 pages, of our Catalogue of 



Books on Chemistry, Chemical 

 Technology in Physics. 



It is arranged by subjects, and includes all the 

 standard books in Chemical and Physical Science, as 

 well as the recent 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. 



Ijij^esnoji 



Horsford's Acid Phosphate 



Is the most effective and agreeable 

 remedy in existence for preventing in- 

 digestion, and relieving those diseases 

 arising from a disordered stomach. 



D. W. W. Gardner, Springfield, Mass., 

 says : "I value it as an excellent preventive of 

 indigestion, and a pleasant acidulated drink 

 when properly diluted with water and sweet- 

 ened." 



Descriptive pamphlet free on application to 

 Rumford Chemical Works, Providence, R. I, 



Bewart of Substitutes and Imitations. 



For sale by all Druggists. 



The XIxiivers-uLzxi Clock 



represents the Universe. It shows the earth revolving round 

 its axis, giving the time at the point passing the sun, the 

 stars in their proper position, and their rising and setting. 



The Northern Hexnispliere Clock 



snows at a glance the time at every place between the North 

 Pole and Equator. 



UNIVERSUIVI CLOCK CO., 1 BEACON ST.. BOSTON, MASS. 



HOUGH'S "AiVIEBICAN WOODS" 



A publication illustrated by actual specimens. Prepara 

 TioNS OF Woods fok Stereopticon and Microscope, Speci 

 MENS OF Woods for Class Use, Etc. If you are interested 

 in woods or trees in any way, send for our circulars and 

 sample specimens. Address 



R. B. HOUGH, LOWVILLE, IM. Y. 



in the country to-day offers so high a class 01 

 Indian Stone" Relics as I am now ottering to 

 advanced collectors, having recently bought 

 several collections, giving every type of Ar- 

 row and Spear Heads from J4 inch to 7 inches. Drills, Axes, 

 Celts, Pipes, Mortars, Pestles, Hematites. Banner Stones, Amu- 

 lets, also, European Stone Relics. Nothing surpasses and few 

 approach my stock of 15,000 pieces. Goods sent on selection. 

 Catalogue for stamp Also Catalogue, No. S, Mi.nerals, Fos- 

 sils, etc. L. W. STILWELL, Dead wood, South Dak. 



COLLECTIONS OF MIISTERALS. 



Scientillcally selected, arranged and labeled. Uneqalled tor beauty and practical value. 



MINERALS FOR LABORATORY WORK. 



Sold by the pound at very low prices. 



CABINET SPECIMENS in greatest variety. 



124-page Illustrated Catalogue, 25c. in paper, .50c. in cloth. 

 44-page Illustrated Price-Lists, 4c. ; Butlelins and Circulars Free. 



GEO. L. ENGLISH & CO., Mineralogists, 64 East 12th St., New York. 



