Produced by Olaf Voss, Don Kretz, Juliet Sutherland, Charles Franks and the Distributed Proofreaders Team [Illustration] SCIENTIFIC AMERICAN SUPPLEMENT NO. 401 NEW YORK, SEPTEMBER 8, 1883 Scientific American Supplement. Vol. XVI, No. 401. Scientific American established 1845 Scientific American Supplement, $5 a year. Scientific American and Supplement, $7 a year. * * * * * TABLE OF CONTENTS. I. CHEMISTRY.--On the Different Modifications of Silver Bromide and Silver Chloride. Analysis of New Zealand Coal. On the Determination of Manganese in Steel, Cast Iron, Ferro-manganese, etc. Manganese and its Uses. Ozokerite or Earth-wax. By WILLIAM L. LAY. A valuable and instructive paper read before the New York Academy of Sciences.--Showing the nature, sources, and applications of this remarkable product. On the Constitution of the Natural Fats. II. ENGINEERING AND MECHANICS.--Improved Spring wheel Traction Engine.--With two engravings. An Improved Iron Frame Gang Saw Mill.--With one large engraving. The Heat Regenerative System of Firing Gas Retorts.--Siemens' principle.--As operated at the Glasgow Corporation Works.--With two engravings. A New Gas Heated Baker's Oven. III. TECHNOLOGY.--How to Produce Permanent Photographic Pictures on Terra Cotta, Glass, etc.--With recipes and full directions. How to Make Paper Photo Negatives.--Full directions. Some of the Uses of Common Alum. An Improved Cloth Stretching Machine.--With an engraving. Purification of Woolen Fabrics by Hydrochloric Acid Gas. Apparatus for Preventing the Loss of Carbonic Acid in Racking Beer.--With an engraving. IV. ELECTRICITY.--Application of Electricity to the Bleaching of Vetable Textile Materials.--With figure of apparatus. Table Showing the Relative Dimensions, Lengths, Electrical Resistances, and Weights of Pure Copper Wires. V. ASTRONOMY.--The Solar Eclipse of 1883.--An interesting abstract from a report of C. S. HASTINGS (Johns Hopkins University), of the American Astronomical Exhibition to the Caroline Islands. VI. NATURAL PHILOSOPHY.--Recent Experiments Affecting the Received Theory of Music.--An interesting paper descriptive of certain experiments by President Morton, of Stevens Institute. The Motions of Camphor upon Water.--With an engraving. VII. ARCHITECTURE.--Suggestions in Village Architecture.-- Semidetached villas.--Bloomfield crescent.--With an engraving. Specimens of Old Knocking Devices for Doors.--Several figures. VIII. ARCHÆOLOGY.--A Buried City of the Exodus.--Being an account of the recent excavations and discoveries of Pithom Succoth, in Egypt.--With an engraving. The Moabite Manuscripts.