Produced by Olaf Voss, Don Kretz, Juliet Sutherland, Charles Franks and the Online Distributed Proofreading Team. [Illustration] SCIENTIFIC AMERICAN SUPPLEMENT NO. 275 NEW YORK, APRIL 9, 1881 Scientific American Supplement. Vol. XI, No. 275. Scientific American established 1845 Scientific American Supplement, $5 a year. Scientific American and Supplement, $7 a year. * * * * * TABLE OF CONTENTS. I. ENGINEERING AND MECHANICS.--The Various Modes of Transmitting Power to a Distance. (Continued from No. 274.) By ARTHUR ARCHARD. of Geneva.--II. Compressed Air.--III. Transmission by Pressure Water.--IV. Transmission by Electricity.--General Results The Hotchkiss Revolving Gun Floating Pontoon Dock. 2 figures.--Improved floating pontoon dock II. TECHNOLOGY AND CHEMISTRY.--Wheat and Wheat Bread. By H. MEGE MOURIES.--Color in bread.--Anatomical structure and chemical composition of wheat.--Embryo and coating of the embryo.-- Cerealine--Phosphate of calcium.--1 figure, section of a grain of wheat, magnified. Origin of New Process Milling.--Special report to the Census Bureau. By ALBERT HOPPIN.--Present status of milling structures and machinery in Minneapolis by Special Census Agent C. W. JOHNSON.--Communication from GEORGE T. SMITH. Tap for Effervescing Liquids. 1 figure. London Chemical Society.--Notes.--Pentathionic acid, Mr. VIVIAN LEWES.--Hydrocarbons from Rosin Spirit. Dr. ARMSTRONG.--On the Determination of the Relative Weight of Single Molecules. E. VOGEL.--On the Synthetical Production of Ammonia by the Combination of Hydrogen and Nitrogen in the Presence of Heated Spongy Platinum, G. S. JOHNSON.--On the Oxidation of Organic Matter in Water, A. DOWNS. Rose Oil, or Otto of Roses. By CHAS. G. WARNFORD LOCK.--Sources of rose oil.--History--Where rose gardens are now cultivated for oil.--Methods of cultivation.--Processes of distillation.--Adulterations A New Method of Preparing Metatoluidine. By OSCAR WIDMAN. III. AGRICULTURE, HORTICULTURE, ETC.--The Guenon Milk Mirror. 1 figure. Escutcheon of the Jersey Bull Calf, Grand Mirror. Two Good Lawn Trees Cutting Sods for Lawns Horticultural Notes: New apples, pears, grapes, etc.--Discussion on Grapes. Western New York Society.--New peaches.--Insects affecting horticulture.--Insect destroyers. Observations on the Salmon of the Pacific. By DAVID S. JORDAN and CHARLES B. GILBERT. Valuable census report. IV. LIGHT, ELECTRICITY ETC.--Relation between Electricity and Light. Dr. O. T. Lodge's lecture before the London Institute. Interesting Electrical Researches by Dr. Warren de La Rue and Dr. Hugo Miller. Telephony by Thermic Currents