24 
PHARMACEUTICAL BOTANY 
fixing fluids but has very little hardening power. It is employed 
in saturated aqueous solution. 
Corrosive sublimate (HgCb) in 0.2 per cent, aqueous or alcoholic 
solution penetrates and hardens rapidly but doesn’t give as sharp opti¬ 
cal differentiation as the others considered. 
Absolute alcohol can be employed for very small objects that are 
dry. If the objects are moist shrinkage will follow. 
Carnoy fluid, consisting of 6 parts absolute alcohol, 3 parts 
formaldehyde and 1 part of glacial acetic acid, can also be used for 
fixing small objects. It has the advantage of fixing these in about 
10 minutes. Moreover the objects can be carried directly to abso¬ 
lute alcohol, thence to Paraffin and imbedded. 
For most materials the Flemming fluids have proven very satis¬ 
factory and are the most generally employed. They are of two 
classes, viz; 1. Those that simply involve chromic acid and acetic 
acid (the chrome-acetic fluids) and 2. Those that involve chromic 
acid, acetic acid and osmic acid (the Chrome-Osmium-Acetic Fluids). 
The formulae follow: 
Strong 
Medium 
Weak 
CHROME-ACETIC FLUIDS 
{ 1 per cent. Chromic acid solution... 
| Glacial acetic acid. 
I 1 per cent. Chromic acid solution. . 
1 per cent. Glacial acetic acid. 
[ Distilled water. 
1 1 per cent. Chromic acid solution. . 
1 per cent. Glacial acetic acid. 
Distilled water. 
CHROME-OSMIUM-ACETIC FLUIDS 
I 1 per cent. Chromic acid solution. 
Strong | 2 per cent. Osmic acid solution. 
( Glacial acetic acid. 
1 per cent. Chromic acid solution. 
Tir , 1 per cent. Osmic acid solution. 
1 per cent. Acetic acid solution. 
Distilled water. 
100 mils 
1 mil 
70 mils 
1 mil 
29 mils 
25 mils 
10 mils 
65 mils 
75 mils 
20 mils 
5 mils 
25 mils 
10 mils 
10 mils 
55 mils 
