The use of alternating currents for submarine marine cable transmission

This paper contains the results of experiments performed by members of the Signal Corps Research Laboratory, Bureau of Standards, in an attempt to develop a method or methods of signal transmission over submarine cables which would permit of a more effective use of existing cable systems.In the method proposed and developed, signals are transmitted by means of alternating currents simultaneously with the normal battery of direct-current operation of the cable. Currents of several different frequencies may be used, reserving a given frequency for each message, and by tuning or equivalent methods at the receiving end these messages may be separated, so that the simultaneous transmission of a number of messages is redered possible.Accurate determination of the fundamental physical properties of a particular cable for different frequencies has been accompalished, and the results are given herewith. From these physical properties accurate calculations for any length of cable can be made, so that the design of proper apparatus becomes purely a laboratory problem.Actual trial of the proposed alternating-current method was made covering distances up to approximately 700 kilometres, with results which were in all cases completely satisfactory, indicating that the method is an entirely feasible one, and one which will render cables of this length, and undoubtedly of several times this length, much more useful.     

Determination of silver ion with various concentrations of hydrogen chloride as precipitant

It has been shown that 0.15 N hydrogen chloride solution is most suitable for employment as precipitant in the quantitative estimation of silver ion, this procedure reducing adsorption to a minimum.When a more dilute solution of reagent is applied, there is a tendency for a portion of the silver to remain dissolved.When hydrogen chloride possessing a greater concentration than 0.15 N is utilized in this determination, adsorption of Cl? ion, and, to a lesser extent, of Ag+ ion, readily occurs.The data presented here have been obtained by careful application of a recognized method, during the course of which temperature effect, and solubility data were given due consideration. Meticulous nephelometric examination was subsequently accorded each experimental sample prior to the calculation of results.