The Determination of Fibrinogen by Precipita- Tion with Sodium Sulfate Compared with the Precipitation of Fibrin by the Addi- Tion of Calcium Chloride

Recently we have had occasion to make a considerable number of determinations of fibrin by the method of Cullen and Van Slyke, which we have modified slightly (1). Simultaneous determinations were made by precipitating fibrinogen with 10.6 per cent sodium sulfate at 37°C and some determinations by the methods of Gram (2) and of Foster and Whipple (3). The fundamental procedures of various recent methods for the determination of fibrin and fibrinogen are as follows: