| Abstrakt: |
Making tuberculin dilutions by the usual methods entails taking a large quantity of tuberculin, 0.2 c.c., thereby making it possible to get but five diluted solutions from 1 c.c., and it is usual to measure it in a pipette of rather large caliber. I deem it worth while to present a more accurate and a more economical method.The counting pipette for red blood corpuscles is used for measuring the quantity of tuberculin taken, but the tuberculin and diluent are not mixed in the cell of the pipette. My pipette holds 0.9 c.c. Having measured out that quantity of the diluent in a small graduate (5 c.c.), I draw tuberculin up to the mark (0.5) on the stem of the pipette and expel it into the sterile graduate containing the diluent. This gives me a dilution of 1 to 200. Adding to this four equal volumes of the diluent I |
