A New Microcolorimetric Apparatus and a Method for Determination of Total Blood Volume

Abstract

IT is a matter of importance in physiology to construct an apparatus by which it is possible to determine the concentration of very weak dye-solutions in small quantities, without any decrease in its layer-thickness. In my apparatus a capillary tube is used with a volume of 10 cubic millimetres and a length of 20 millimetres. In this capillary tube is placed the dye-solution, the concentration of which is to be determined. The tube is covered with a black paper-hull to keep out the light from the side. The tube is hung vertically by a holder of simple construction on the object stage. This dye-solution is enlarged by the microscope, from which the eye-piece has been removed. In its place there is a prism-system, which is similar to the upper part of a Duboscq colorimeter. The prism cuts off the rays in one half of the field of vision. Under the other half of this prism is fastened a wedge in order to compare the concentrations of the dye solutions. This wedge can be moved horizontally by a screw in front of a scale. Under the wedge is a light-filter, a diaphragm and an illuminating mirror from which the rays are directed through the filter, diaphragm and wedge to the other half of the eyepiece; the scale is determined by the aid of dye solutions of defined concentration. The unknown dye solution is put into the capillary tube. The wedge is screwed until there is an equalization of colour intensity and so the concentration of dye solution can be easily calculated. In this way one can estimate the colour concentration of dye solution between 1: 10,000–1: 100,000. It can be used also for determination of weaker and stronger dye solutions by changing the length of the capillary tube.