TUBERCLE. 73 
5- Methylene blue. (Saturated watery solution or 
Loffler’s blue). 
6. A metal (iron or copper) plate. The exact dimen- 
sions do not matter, but 8 x 4 x }in. is a convenient 
size. It should be mounted upon a tripod. This slab 
is not absolutely necessary, but it is a very great advan- 
tage. 
Method.—We will suppose that the film has been 
prepared by one of the methods described subsequently 
and fixed by heat. 
1. Place it upon the metal plate and heat the latter 
by the flame. Flood the slide with carbol-fuchsin and 
let the heat continue until the stain steams, but do not 
allow it to dry up; let this go on for from three to five 
minutes. If the stain shows signs of drying up adda 
little more; if it begins to boil slide it along the plate 
away from the flame, or remove the latter for a short 
time. 
If you have no metal plate it is possible to hold the 
slide with a pair of forceps, but in this case the film is 
most conveniently made on a cover-glass. 
Remember not to let the stain dry up. 
2. Remove the slide from the plate with the forceps 
and wash it under the tap or in a bowl of water. 
3. Put it into the bottle containing the dilute acid. 
After three or four minutes withdraw it and again wash. 
If much pink colour comes back re-insert it in the acid 
for a short time and again wash. ‘The process must be 
repeated until the film only shows a slight pink tinge. 
4. Now apply the methylene blue for a minute or so. 
5. Wash, dry with blotting paper and then by gentle 
heat. Apply a drop of balsam and cover. 
