[Illustration] SCIENTIFIC AMERICAN SUPPLEMENT NO. 531 NEW YORK, MARCH 6, 1886 Scientific American Supplement. Vol. XXI, No. 531. Scientific American established 1845 Scientific American Supplement, $5 a year. Scientific American and Supplement, $7 a year. * * * * * TABLE OF CONTENTS. I. CHEMISTRY AND METALLURGY.--Annatto.-Analyses of the same.--By WM. LAWSON Aluminum.--By J.A. PRICE.--Iron the basis of civilization.-- Aluminum the metal of the future.--Discovery of aluminum.--Art of obtaining the metal.--Uses and possibilities II. ENGINEERING AND MECHANICS.--The Use of Iron in Fortification. --Armor-plated casements.--The Schumann-Gruson chilled iron cupola.--Mougin's rolled iron cupola.--With full page of engravings High Speed on the Ocean Sibley College Lectures.--Principles and Methods of Balancing Forces developed in Moving Bodies.--Momentum and centrifugal force.--By CHAS.T. PORTER.--3 figures Compressed Air Power Schemes.--By J. STURGEON.--Several figures The Berthon Collapsible Canoe.--2 engravings The Fiftieth Anniversary of the Opening of the First German Steam Railroad.--With full page engraving Improved Coal Elevator.--With engraving III. TECHNOLOGY.--Steel-making Ladles.--4 figures Water Gas.--The relative value of water gas and other gases as Iron-reducing Agents.--By B.H. THWAITE.--Experiments.--With tables and 1 figure Japanese Rice Wine and Soja Sauce.--Method of making IV. ELECTRICITY, MICROSCOPY, ETC.-Apparatus for demonstrating that Electricity develops only on the Surface of Conductors.--1 figure The Colson Telephone.--3 engravings The Meldometer.--An apparatus for determining the melting points of minerals Touch Transmission by Electricity in the Education of Deaf Mutes.--By S. TEFFT WALKER.--With 1 figure V. HORTICULTURE.--Candelabra Cactus and the California Woodpecker.--By C.F. HOLDER.--With 2 engravings How Plants are reproduced.--By C.E. STUART.--A paper read before the Chemists' Assistants' Association VI. MISCELLANEOUS--The Origin of Meteorites.--With 1 figure * * * * * THE USE OF IRON IN FORTIFICATION. Roumania is thinking of protecting a portion of the artillery of the forts surrounding her capital by metallic cupolas. But, before deciding upon the mode of constructing these formidable and costly affairs, and before ordering them, she has desired to ascertain their efficacy and the respective merits of the chilled iron armor which was recently in fashion and of rolled iron, which looks as if it were to be the fashion hereafter. [Illustration: FIG. 1.--MOUGIN'S ROLLED IRON TURRET.]