At present thecolititre of water is almost universally determined by fermentation tests in sugar-containing media; the fermentation method of Eijkman (glucose-peptone solution at 46°2) and that of Bulir (neutral-red mannite bouillon at 46°) are current in many European countries, while in America fermentation in lactose bouillon at 37° is the standard test. Fermentation tests at 37° in lactose-containing media with the addition of bile and bactericidal dyes are also widely used (Great Britain, America).