DYE1NQ, 



of lime water, or as sulphate of lime dissolved in 

 water. 



Although all the metallic oxides have an affinity 

 for cloth, only two, the oxides of tin and of iron, 

 are much used as mordants. 



The oxide of tin is one of the most valuable mor- 

 dants, and is the only one by which scarlet, the 

 brightest of all colours, can be produced. It was 

 first brought to London by Karsten, a German, in 

 1543-I which period forms an epoch in the history 

 of dyeing. 



Proust has shown that tin has two oxides. The 

 first, or grey oxide, consists of seventy parts of tin, 

 and thirty oxygen : the second, or white oxide, of 

 sixty parts of tin, and forty oxygen. The first ox- 

 ide absorbs oxygen rapidly from the air, andbecomes 

 converted into the white oxide. It is, therefore, 

 the white oxide alone that is the real mordant ; 

 since if the first were applied to cloth, as it proba- 

 bly often is, it must soon be converted into the 

 white oxide by absorbing oxygen. 



Tin is used as a mordant in three states ; dis- 

 solved in mtro-muriatic acid*, in acetous acid, and 

 iri a mixture of sulphuric and muriatic acids. 



- . A* < i , 



That commonly used by the dyers, and called by 

 them spirit of tin, is the nitro-muriate. It is pre- 

 pared by dissolving granulated tin in very dilute 

 nitric acid, or what is called single aquafortis : and 

 a quantity of muriate of soda, or muriate of am- 

 monia, is added. These salts are decomposed by 

 the nitric acid, and the muriatic acid is set free, 

 sometimes to economize the nitric acid, a quan- 

 tity of sulphuric acid is added, just sufficient to 

 saturate the base of the muriate of soda. 



When nitro-muriate of tin is used as a mordant, 

 it is dissolved in a large quantity of water, and 



