THE VENETIAN TURPENTINE METHOD 107 



4. Ten per cent Venetian turpentine in an exsiccator until the turpentine 

 becomes thick enough for mounting. 



5. Mount in the Venetian turpentine. 



Even after the method became established, there occurred a period 

 of several years during which it was practically impossible to get a 

 Venetian turpentine suitable for histological use. Consequently, it 

 was necessary to resort to glycerin jelly or to try various schemes for 

 bringing material into Canada balsam ; but good Venetian turpentines 

 are again available and are even more satisfactory than those which 

 established the method in popular favor. We have tested two brands 

 which are giving uniform and excellent results: these are the "Venice 

 Turpentine (True)," sold by the Fuller-Morrison Company, of Chica- 

 go; and the ''Turpentine Venetian" (No. 2605), sold by the National 

 Anilin and Chemical Company, of New York. There are probably 

 other good turpentines and still others are likely to appear. 



The general outline, just given, is not sufficiently definite for a 

 working introduction. The following concrete examples, describing 

 the use of Venetian turpentine with an aqueous stain, with an alco- 

 holic stain, and with a combination of aqueous and alcoholic stains, 

 will be more practical than general directions. The steps from fixing to 

 mounting, as used with an aqueous stain, will be described first, since 

 this will introduce the method in its least complicated form. 



Heidenhain's iron-haematoxylin. — Using Spirogyra as a type, pro- 

 ceed as follows: 



1. Fix 24 hours in chromo-acetic acid. 



1 per cent chromic acid 100 c.c. 



Glacial acetic acid 3 c.c. 



The volume of the fixing agent should be at least 50 times that of the 

 material to be fixed. 



2. Wash in running water 24 hours. (After this washing in water, the 

 material may be run up to 85 per cent alcohol for hardening, and then 

 back to water.) 



3. Two per cent aqueous solution of iron-alum (ammonia sulphate of 

 iron), 4 hours. ■» 



4. Wash in running water, 20 minutes. 



5. Stain overnight, or 24 hours, in ^ per cent aqueous solution haema- 

 toxyUn. 



6. Wash in water, 20 minutes. 



