694 : PHARMACEUTICAL BOTANY 
paraffin (m.p. 54° to 55°C.) directly to the beaker or other 
receptacle containing it and placing the beaker in a paraffin 
oven at 56° for several hours. Then replace the butyl-alcohol- 
paraffin mixture with pure. melted paraffin for 3 hours and 
embed. 
Formalin-alcohol, consisting of from 2 to 6 per cent. of formalin 
in 50 to 70 per cent. alcohol, is a good fixing and preserving agent 
for materials which are not of very delicate texture. It should 
not be used for unicellular or filamentous alge and fungi. For 
these 2 to 6 per cent. aqueous solutions of formalin have given 
good results. Material can be left in the formalin solutions 
until required for use, provided care be exercised in storing it in 
air-tight containers. 
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 formulz follow: 
CHROME-ACETIC FLUuIps 
Song : per cent. Chromic acid solution......... 100 ce. 
Glacial meetie atid sat oe eres ice 
1 per cent. Chromic acid solution......... 1Oee; 
Medium f per cent: Glacial acetic acid) vi): toeei 
Distilled Water ss SE Oa A oes 29 ec 
1 per cent. Chromic acid solution......... 25.ce: 
Weak 1 per.cent. Glacial acetic acid #2 occur. . 10 cc. 
Distilled water oss, bia dae 8 65 cc. 
CHROME-OSMIUM-ACETIC _FLUuIDs 
1 per cent. Chromic acid solution......... 7500: 
Strong , per cent. Osmic acid solution........... 20 cc. 
Glacial acetic acid 6.1) ar, ee aes 7c. 
1 per cent. Chromic acid solution......... 25 cc. 
Weak ss cent. Osmie acid solution; 210.5 10 cc. 
ea ee ; 
1 per cent. Acetic acid solution. .......... 10 cc. 
Disalled waters.) hn ee ee 55:cc. 
