304 BACTERIOLOGY. 
held in the Cornet forceps, covered and kept covered 
completely with fluid while steamed for two minutes 
over the flame. 
The Koch-Ebrlich solution decomposes after having 
been made four a time, so that it must be freshly pre- 
pared as needed. Solutions older than fourteen days 
should not be used. The advantages in using Ziehl’s 
carbol-fuchsin solution are that it keeps well and is 
more convenient for use in small quantities. 
Another method, which is often of value on account 
of its simplicity and rapidity of performance, is that 
of Frinkel as modified by Gabbett. This consists in 
staining the cover-glass ‘‘smear’’ with steaming Ziehl’s 
carbol-fuchsin solution for from one to two minutes, 
and then after washing in water placing it from one- 
half to one minute directly in a second solution which 
contains both the acid for decolorizing and the contrast 
stain, This second solution consists of— 
Sulphuric acid. , ‘ , . 25 ce. 
Methylene-blue in substance : . 2 grammes. 
Water : * ; ; 3 . Tdce 
It is then washed with water and is ready for examina- 
tion. The tubercle bacilli will remain red as stained by 
the fuchsin, while all other bacteria will be tinted blue. 
When the number of tubercle bacilli in sputum is 
very small they may easily escape detection. Methods 
have, therefore, been suggested for finding them under 
these circumstances. Ribbert proposed the addition. to 
the sputum of a 2 per cent. solution of caustic potash 
and boiling the mixture. The mucus is dissolved, and 
when the mixture is placed in a conical glass vessel any 
bacilli present are deposited at the bottom, and may be 
found in the sediment after removing the supernatant 
