328 Dr. Thomas Thomson on [May 



Sulphate of lead is mixed with chloride of tin, and printed 

 upon bronzed cloth. A double decomposition takes place, 

 and chloride of manganese with peroxide of tin is formed. 

 When the cloth is washed in water the chloride of manganese 

 dissolves and is carried away, but the tin remains adhering 

 to the cloth, and along with it the sulphate of lead. This 

 salt is afterwards decomposed by lime, and the oxide of lead 

 adheres to the cloth, and becomes yellow when the cloth 

 passes through a solution of bichromate of potash. 



Instead of sulphate of lead, other substances may be 

 deposited in a similar manner. The pale chromate of lead, 

 for example, may be mixed with protochloride of tin, and 

 remain so for some hours without material injury. A yel- 

 low is thus produced without the necessity of any subsequent 

 operation. The lake from Brazil wood or cochineal may 

 also be employed to produce a pink discharge upon bronze, 

 that of logwood a purple, &c. But prints formed in this 

 way cannot be washed, even in cold water, with any degree 

 of freedom. 



Red oxide of iron is permanently fixed upon bronzed 

 cloth, as may be seen in the specimen of cloth marked 

 No. 9, by printing a solution of protochloride of iron on the 

 parts of the cloth that are to undergo the alteration. In a 

 few hours the manganese and iron change places, the iron 

 being deposited on the cloth in the state of peroxide, while 

 the chloride of manganese is removed by washing. 



11. Red and Chocolate Resist on Pale Blue. 



If the aluminous mordant, with the addition of a little 

 verdigris and soft soap, and thickened with gum and pipe- 



