Properly speaking, block-tin means tin in blocks, or square massive ingots; but in the sense in which it is used by ignorant workmen, it is iron plated with tin, which renders it more durable, as tin will not so easily rust. Tin alone, however, would be too soft a metal to be worked for common use, and all tin-vessels and utensils are in fact made of plates of iron, thinly coated with tin, which prevents the iron from rusting.
CAROLINE.
Say rather oxydating, Mrs. B.—Rust is a word that should be exploded in chemistry.
MRS. B.
Take care, however, not to introduce the word oxydate, instead of rust, in general conversation; for you would probably not be understood, and you might be suspected of affectation.
Metals differ very much in their affinity for each other; some will not unite at all, others readily combine together, and on this property of metals the art of soldering depends.
EMILY.
What is soldering?
MRS. B.
It is joining two pieces of metal together, by a more fusible metal interposed between them. Thus tin is a solder for lead; brass, gold, or silver, are solder for iron, &c.