PHARMACEUTICAL BOTANY 



fixing fluids but has very little hardening power. It is employed 

 in saturated aqueous solution. 



Corrosive sublimate (HgCl 2 ) 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 i 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; i. 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: 



CHROME-ACETIC FLUIDS 



i per cent. Chromic acid solution. . .100 mils 

 Strong , . , . . . ., 



Glacial acetic acid i mil 



i per cent. Chromic acid solution 70 mils 



Medium i per cent. Glacial acetic acid i mil 



Distilled water 29 mils 



i per cent. Chromic acid solution . . 25 mils 



Weak i per cent. Glacial acetic acid 10 mils 



Distilled water 65 mils 



CHROME-OSMIUM-ACETIC FLUIDS 



i per cent. Chromic acid solution 75 mils 



Strong 2 per cent. Osmic acid solution 20 mils 



Glacial acetic acid 5 mils 



i per cent. Chromic acid solution 25 mils 



i per cent. Osmic acid solution 10 mils 



Weak . . , 



i per cent. Acetic acid solution 10 mils 



Distilled water 55 mils 



