208 TECHNIC, 



Osmic acid (two per cent solution) 



12 CC. 



Glacial acetic acid 3 cc. 



Especially valuable for delicate tissues. Time, 

 twenty-four hours ; dehydrate with alcohol. 



HARDENING REAGENTS. 



Midler's fluid, corrosive sublimate solution, chro- 

 mic acid, and others of the reagents named above may 

 be used for hardening purposes. For general use, iai/- 

 cohol will be found invaluable. The tissue should be 

 passed through increasing strengths of alcohol, seventy 

 per cent, eighty per cent, ninety per cent ninety-five 

 per cent, and absolute. It should be allowed to re- 

 main twenty- four hours in each, except that one to six 

 hours will suffice for absolute alcohol. Ethyl alcohol 

 should be used, or, in lieu of this, methyl alcohol 

 makes a good substitute. To prepare absolute alcohol, 

 dehydrated copper sulphate may be added to ethyl or 

 methyl alcohol. This will absorb the water present. 



EMBEDDING MEDIA. 



Paraffin and celloidin are extensively used for em- 

 bedding tissue. 



