Porges-Meier reaction is a precipitation test used in the diagnosis of syphilis.
It is an early flocculation test for syphilis.
Precipitate formation takes place in a serum by the addition of a solution of sodium glycocholate. This reaction, according to Otto Porges, only occur in syphilis.
Reference:
http://ajp.psychiatryonline.org/cgi/content/abstract/65/4/653