**Farber's test** (Farrab's test), a modification of the Sono-Sternberg test, for the differential diagnosis of tuberculosis and pharyngeal diphtheria, is performed as follows. At the patient's request, take a full breath, then drink a few sips of a chilled sodium chloride solution and hold your breath. After a quarter of a minute, a slow stream injection of a 5% starch solution begins over 3-5 minutes. At the same time, uniformly dosed breathing is done for the same time - a series of intense inhalations and exhalations. Under these conditions, the appearance of foamy, bloody saliva after a 2-3-minute break occurs mainly from the epiglottis of the pharynx.
**In practice, doctors do not use this method, since in any case it will not be able to determine the source, that is, whether the source is diphtheria or tuberculosis.**