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January 28, 1928


Author Affiliations

Seymour Coman Fellow in Medical Chemistry, Kent Chemical Laboratory, University of Chicago; Charles Schweppe Fellow, St. Luke's Hospital CHICAGO
From the Henry Baird Favill Laboratory of St. Luke's Hospital.

JAMA. 1928;90(4):259-260. doi:10.1001/jama.1928.02690310011005

Mishulow and Krumwiede1 have recently suggested a colorimetric method for the estimation of the strength of bacterial toxins by means of titration with auric chloride, approximately as follows:

Two cubic centimeters of a 1:4 dilution of the toxin sample is added to each of a series of micro test tubes

containing graded volumes of 1 per cent auric chloride.

The contents of the tubes are mixed and warmed for forty minutes at 50 C.

At the end of this interval, the mixtures containing the smallest volumes of auric chloride are

observed to have undergone little notable change. Those representing the largest volumes of the reagent may have produced heavy flocculi. Intermediately, some of the mixtures may have developed a blue coloration (by transmitted light), and some a purple coloration, and some a green.2 The volume of auric chloride that has produced the most intense green color is presumed

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