By Prof. H. C. Boltom.--Chemical societies, new elements, atomic weights, spectrum analysis, form of matter, affinity and chemical action, electrolytic thermal chemistry, new views of chemical reaction, chemical dynamics, chemical physics, liquefaction of gases, chemical industries, nomenclature, progress in organic chemistry, the aromatic series of compounds, synthesis of organic compounds, physiological and sanitary chemistry, tendency of modern chemistry. Contained in SCIENTIFIC AMERICAN SUPPLEMENT, No. =546.= Price 10 cents. To be had at this office and from all newsdealers. Handle for Rubber Stamps. Four stamps and dater on one handle. Simple and convenient. Send 50 cents for sample and trade price list. G. B. SHOLES, 308 N. 6th Street, St. Louis. To Manufacturers --SEEKING A NEW LOCATION.-- To parties already established, or about to form new companies, _special inducements_ will be offered, and correspondence is solicited with a view to locating in the thriving city of Brockton, Mass., on the old Colony R. R., 30 minutes from Boston and one hour's ride from Fall River. Present population 22,000, 40 per cent increase in the past 5 years. Address SECRETARY BUSINESS MEN'S CLUB, Brockton, Mass. THE CHEAPEST AND BEST: PHOTO ENGRAVING CO. 67 PARK PLACE, NEW YORK. ENGRAVING FOR ALL ILLUSTRATIVE AND ADVERTISING PURPOSES SOLID EMERY WHEELS.--By T. D. Paret.--Early forms of emery wheels and their defects. Vulcanite wheels. The tanite wheels. Testing of tanite wheels at Stroudsburg. Best working speeds for emery wheels. Bursting of emery wheels. Tests for emery wheels. Comparative merits of American and English emery wheels. With 2 engravings. Contained in SCIENTIFIC AMERICAN SUPPLEMENT, No. =538.= Price 10 cents. To be had at this office and from all newsdealers. THE PHONOGRAPHIC MAGAZINE =Jerome B. Howard=, Editor. A 24 page Monthly. The authentic exponent of the Benn Pitman System of Phonography. $1.50 per annum. Specimen copy free. =The Phonographic Institute, Cincinnati, O.= ICE & REFRIGERATING Machines. York Patent. =YORK MFG. CO., York, Pa.= PULLEYS, HANGERS, FRICTION CLUTCHES. PROGRESS MACHINE WORKS, A. & F. BROWN, 43 Park Place, N. Y. REID'S LIGHTNING BRACE SPECIALLY DESIGNED FOR LIGHT BORING, SCREW DRIVING &c. [Illustration] NICKEL PLATED, WITH 2 BITS ROSEWOOD TRIMMINGS 2.75 POST PAID. =A. H. REID.= 1635 BARKER ST. PHILA. Agents Wanted. Transmission of Power. Suspension Bridges, Tramways, and other applications of WIRE ROPE Trenton Iron Co. WORKS and OFFICE, TRENTON, N. J. New York Office--COOPER, HEWITT & CO., 17 Burling Slip. Philadelphia Office--22 and 24 North Fourth Street SEEDS GIVEN AWAY! A package of Mixed Flower seeds (500 kinds), with PARK'S FLORAL GUIDE, all for 2 stamps. Every flower-lover delighted. Tell all your friends. =G. W. PARK, Fannettsburg, Pa.= [Illustration] Send at once. This notice will not appear again.