Greenfield and Anderson1 have recently described a simple technic for the sedimentation of tubercle bacilli in the sputum. In brief, this method consists in placing a small amount (5 c.c.) of sputum in a centrifuge tube, adding two volumes of 1 per cent. sodium carbonate in 1 per cent. phenol (carbolic acid), shaking well, and placing in the incubator for from twelve to twenty-four hours. The tubes are then centrifuged for about fifteen minutes and smears made from the sediment after pouring off the supernatant fluid.
The advantages claimed by the author for this method are: (1) rapidity; (2) sterility of sputum when taken from the incubator, and (3) the resemblance of the films to direct smears. They also made controls of their method, using the full technic of Ellerman and Erlandsen for comparison, and report a distinct advantage in the simplified method.
This technic was recently tried out
Woolley S. A SIMPLE TECHNIC FOR CONCENTRATING SPUTUM. JAMA. 1920;74(8):525. doi:10.1001/jama.1920.26210080001009