The use of the phenolsulphonephthalein test of Rowntree and Geraghty1 for estimating renal function has became quite widespread and were it not for the expense of the instruments for determining the percentage of phenolsulphonephthalein the test would enjoy even greater popularity.
The several instruments at present on the market (Duboscq, Autenrieth-Königsberger and Dunning colorimeters) are all reliable, but too expensive for the average practitioner. Acting on the suggestion of Drs. Cabot and Young2 I have devised an instrument which is of simple construction and can be made at small expense. It has proved reliable and will give readings within 2 per cent., when compared with the Geraghty-Rowntree modification of the Autenrieth-Königsberger colorimeter, also when compared with known and measured dilutions of the standard solution.
The instrument consists of a wooden rack to hold 14 small test-tubes (12 × 120 mm., the size used for the Wassermann reaction). Fitting
Brotherhood JS. A SIMPLE COLORIMETER FOR USE IN THE PHENOLSULPHONEPHTHALEIN TEST FOR KIDNEY FUNCTION. JAMA. 1915;LXIV(21):1757. doi:10.1001/jama.1915.25710470005013e