INK GALLS. 



513 



Foreign GallB. 



Ink Galls. 

 Hungarian Gall. 



Dead Sea Apple. 



GallB of Cynips polycera. 



decoction of the leaf, though when made with hot, but not boiling 

 water, it has no right to the name. The solution of copperas is 

 only pale green, and that of the gall is nearly colorless, although 

 when mixed they become deeply black. The old practical joke 

 of forcing a dupe to stain his hands and face black depended on 

 the knowledge of these properties. 



Before the victim went to wash his hands, some of the decoction 

 of galls was poured into the water, while the towel with which 

 he was supplied had been damped with the copperas solution 

 and then dried. The consequence of this combination was, that 

 although the hands and face might be washed perfectly clean, 

 yet, as soon as they were dried with the prepared towel, the union 

 of the two substances produced ink, and both hands and face were 

 deeply stained. 



Now when a gall is cut with a knife, the slightly acid juice acts 

 upon the steel, and so a kind of ink is produced, which -is pale, 

 but still a veritable ink. There is a well-known method of secret 

 writing which depends on this property of iron and tannin, the 

 principle contained in the galls. 



A quill pen is dipped in the solution of copperas, and the re- 

 quired message is written, usually between the lines or among 

 the words of a letter on unimportant subjects, so as to avoid the 



Kk 



