METAL PLATING 57 



"Many other metals rust like iron; that is to say, 

 they are converted into earthy matter by contact 

 with damp air. The color of rust varies according 

 to the metal. Iron rust is yellow or red, that of 

 copper is green, lead and zinc white." 



"Then the green rust of old pennies is copper 

 rust," said Jules. 



"The white matter that covers the nozzle of the 

 pump must be lead rust?" queried Claire. 



"Exactly. The prime difficulty with rust is that 

 it makes metals ugly: they lose their brilliance and 

 polish ; but it works still greater injury. There are 

 harmless rusts which might get mixed with our food 

 without danger : such is iron rust. On the contrary, 

 copper and lead rusts are deadly poisons. If, by 

 mi -chance, these rusts should get into our food, we 

 miirht die, or at least we should experience cruel 

 suffering. We will speak only of copper, for lead, 

 on account of its quick melting, cannot go on the 

 fire and is not used for kitchen utensils. Copper 

 rust, I say, is a mortal poison ; and yet they prepare 

 food in copper vessels. Ask Mother Ambroisine." 



"Very true," said she, "but I always have my eye 

 on my saucepans : I keep them very clean and from 

 time to -time have them replated." 



"I don't understand," put in Jules, "how the 

 work that the tinsmith did this morning could pre- 

 vent the copper rust being a poison." 



"The smith's work will not make the copper rust 

 cease to be a poison," replied Uncle Paul, "but it 

 will prevent the rust's forming. Of the common 

 metals tin rusts the least. Exposed to the air a long 



