GB517462A - Improvements in and relating to means for indicating, recording or registering the content of a substance present in a liquid - Google Patents

Abstract

517,462. Photo-electric testing apparatus. HOLGATE, J. March 15, 1939, No. 8050/38. [Class 40 (iii)] The content of a substance present in a Jiquid, such as the content of chlorine in water, is measured by causing predetermined quantities of the liquid to be introduced successively into an inspection chamber f, Fig. 1, causing each quantity in passing to said chamber to absorb or take up by suction from a source of constant head a determined quantity of a reagent which in proportion to the content of the substance gives to the liquid a corresponding depth of colour or transparency, traversing the inspection chamber by rays falling on a photo-electric cell or like sensitive element, and indicating, recording or registering the variations of current caused in the cell and representing the proportion of the substance in the liquid. As shown, the liquid, e.g. water, comes from a pipe a to a tank b having an overflow pipe b<1> leading to a tank c with a drain pipe c<1>. From tank b the liquid passes through regulating cock d<1> and pipe d to tank e, from which predetermined quantities are successively passed to the inspection chamber f by a syphon g. An overflow pipe e<1> leads from tank e to tank c. The reagent e.g. orthotoluidine is stored in a closed-tank h and passes therefrom through regulating cock h<4> and pipe h<3> to tank i, the two tanks being also connected by a pipe which determines the level of reagent in the tank i. Each time a quantity of liquid is syphoned from tank e, it sucks a given quantity of reagent through pipe i<1> from tank i, and level in said tank falling below bottom of pipe allows reagent to flow from tank h until level in tank i is restored. The inspection chamber f, as shown in Fig. 2, comprises baffles #2 providing a circuitous passage giving time for the reaction of the reagent between the pipe g and transparent windows f<1> through which the rays are passed. The chamber is also provided with an outlet #<3>, #<4>, #<5>, and with cleaning plugs #<6>. As shown in Fig. 5, the cell l is fed from a battery m through a resistance n and is connected by a resistance o to grid p<1> of a valve p, the cathode p<2> of which is connected to a tapping m<1> of the battery. The cathode is heated by a battery p<3>, and the circuit of the anode p<4> includes battery q<4> and measuring instrument r.