The serologic test for syphilis now employed by Vernes depends on a flocculation reaction between the patient's serum and a specially prepared reagent designated as péréthynol.
PREPARATION OF PÉRÉTHYNOL
The preparation of this reagent is somewhat similar to the preparation of the antigen for the modern modified Wassermann test, but there are important differences. Powdered dry muscle of the horse's heart is extracted in a Soxhlet apparatus with ethylene chlorid (C2H4Cl2) in vacuo (manometer reading of 55 to 65 mm.). The muscle residue is then dried at 38 C. in the air and again extracted with absolute ethyl alcohol in vacuo or diluted with additional absolute ethyl alcohol, as may be necessary, until it contains precisely 15 gm. of dry extractives in 1,000 c.c. This solution is péréthynol, the name having been obtained by a contraction of the combined names of the extracting reagents, per
BAYLIS AB, SHEPLAR AE, Mac NEAL WJ. THE VERNES FLOCCULATION TEST FOR SYPHILIS. Arch Derm Syphilol. 1925;12(2):242–252. doi:10.1001/archderm.1925.02370080086007