THE JUNIOR SCOPOMETER

Clinical pathology includes numerous determinations depending on measurements of color or turbidity which it has always been the established practice to make by photometry; i. e., comparison of a test sample's brightness with that of a standard. The present status of colorimetry is somewhat paradoxical because really satisfactory instruments for colorimetric work are becoming available as a result of the constant improvements in photometers of the Duboscq type made by some manufacturers just now when a decided drift toward simpler but inferior optical methods becomes strikingly evident. Undoubtedly, considerations of ease of manipulation, economy of sample, and time account for the turn to handier methods and justify some such technics on the grounds of expediency, but only, be it stressed, if the concomitant sacrifice of precision is adequately appreciated. If the classic experiments of Richtmyer 1 and others are taken as representative of the best photometry, 0.5 per cent may