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Eugen F. A. Obach (1852-1898)
Connected to the Siemens Brothers and Co electrical engineering works.
Died 1898 aged 46.
1899 Obituary 
DR. EUGEN F. A. OBACH was born at Stuttgart in April, 1852, of Swiss parents, his father being an artist.
He was educated at the Real and Polytechnic Schools of his native town, acted temporarily as lecturer on chemistry at the Veterinary College, and subsequently continued his studies in natural science at the University of Leipzig under Professors Kolbe, Wiedeman, Zollner, Fechner and C. Neumann, where he graduated as Ph. D. in 1875.
In the spring of 1875 Dr. Obach commenced his career with the firm of Siemens and Halske, at Berlin, as assistant to Dr. Werner Siemens, and towards the end of the following year he came to England and joined the staff of Messrs. Siemens Brothers, at their Woolwich works, as chief of the experimental department, which post he continued to hold up to the time of his death. Whilst temporarily staying in this country in 1875 he superintended some electrical experiments which were carried out in Ballinskelligs Bay, Ireland, during the completion of the Direct United States Telegraph Cable. He also accompanied the expedition in 1879 oh board Messrs. Siemens Brothers' steamship Faraday, during the laying of the deep-sea portion of the second French Atlantic cable.
He published his first paper in 1875 on the action of the galvanic current on amalgams and alloys, and on the nature of amalgamation currents.
Dr. Obach also displayed considerable inventive ability. He designed a movable coil tangent galvanometer for measuring both current and potential, which is well known as an accurate laboratory instrument; also a dry cell, which has gained a wide reputation for constancy and high output, and is much used for telephone, telegraph, and other purposes. He further invented an apparatus for electrolytically decomposing water into its constituent gases, oxygen and hydrogen, on a practical scale, whereby the gases are obtained in a state of great purity. He also devised an improved form of conducting contact with carbon and other non-metallic electrodes, and a new process for the extraction of gutta-percha from the leaves and twigs of the Isonandra gutta and kindred plants.
Dr. Obach compiled complete tables, which are much used, particularly in Continental laboratories, for readily finding the ratio of the two sections of the slide wire of a Wheatstone bridge.
Other publications, which have appeared in various English and German scientific and technical journals', dealt with the following subjects:-
A battery for constant currents; a lecture apparatus for the demonstration of electric resistance in metallic wires; an electric pressure regulator; a commutator for liquid and gaseous currents; the diffusion of carbonic acid gas through caoutchouc ; the action of manganese peroxide in batteries; a direct relationship between specific inductive capacity and latent heat of vaporisation; the action of phosphorescent light on selenium ; the detection of free sulphur and selenium in carbon disulphide and their approximate quantitative determination, and the behaviour of carbon disulphide towards potassium permanganate, also a method for the complete purification of commercial carbon disulphide.
Dr. Obach delivered several lectures at the German Athemeum, London, the foremost being on the late Sir William Siemens as an inventor and discoverer ; this lecture was subsequently published and favourably reviewed by the press. The other lectures dealt with the "Manufacture, Testing, and Laying of Telegraph Cables," and with the Electric Discharge in Rarefied Gases, and on the Rontgen Rays."
The chief work of Dr. Obach was undoubtedly the study of gutta-percha, which extended over many years, and the results of his great experience and varied knowledge of this substance were embodied in a course of Cantor Lectures, which he delivered before the Society of Arts towards the close of 1897. These lectures, which were fully illustrated by numerous experiments and by a unique collection of rare and valuable specimens, have since appeared in the columns of several technical journals, and have been published in separate form, and translated into German and Dutch. The subject was dealt with in a very exhaustive and comprehensive manner, and the information given is generally considered to be the most important yet published on gutta-percha.
Some time before Ihe preparation of these lectures was commenced, Dr. Obach's health showed signs of failing, and it was mainly due to his indomitable energy and will that he was able to bring them to a successful issue. By the advice of his physician ,he subsequently went abroad and sought relief in a cold-water cure at Brixen, in the Austrian Tyrol, but the course of his disease could not be checked, and he was finally removed to the house of his brother, Emil Obach, at Graz, Styria, where he died on December 27, 1898, at the comparatively early age of forty-six years.
He was elected a Member of this Institution on the 11th of April, 1877.