ID: 
2463
Maker's Name: 
Carl Zeiss, Jena.
Where made: 
Germany
Dimensions: 
91 × 29 × 49.5 cm

Instruments, such as this one, were widely used for concentration measurements in medical applications. Two light beams pass through envettes (missing), containing liquids of interest, and are brought to comparison by an observer, through a system of prisms and coloured filters. Both total light absorption, and absorption in a particular part of the spectrum (colour), can be made.