I have already described the application of a ring or contact method of precipitation test for syphilis.1 Moody2 has confirmed the results and, in a series of 1,500 tests, he obtained a close similarity in the results with the Wassermann and the precipitation tests.
Briefly, the ring method requires the clear, activated or inactivated serum and the 0.4 per cent. cholesterolized antigen first described by Neymann and Gager,3 and later applied in a flocculation test by Kahn.4 The antigen is an alcoholic extract of pig or beef heart that has been freed of ether extractives; cholesterol is then added to make a 0.4 per cent. solution. The antigen is diluted rapidly to 1: 10 with physiologic sodium chlorid solution and placed, by means of a small capillary pipet, into small precipitin tubes approximately 5 mm. in diameter. The serum is placed at the bottom of the
HERROLD RD. THE PRECIPITATION TEST FOR SYPHILIS OF CONCENTRATED ARACHNOID FLUID AND SERUM. JAMA. 1923;81(3):203-206. doi:10.1001/jama.1923.02650030027011