ZINC. 183 



hats, and in other manufactures, is a sulphate of iron. With 

 the prussic acid, iron forms that beautiful paint, known in 

 commerce and the arts by the name of prussian blue. 



Tin must have been known very early, as it is mentioned 

 by Homer, and also in the books of Moses. It is a white 

 metal, of little elasticity, and small specific gravity. It is 

 not very ductile, but so malleable tha't it «iay be beaten out 

 into leaves thinner than paper. Tin-foil, as it is termed, is 

 usually about one-thousandth part of an inch in thickness. 

 Tin enters into combination with many of the metals, and . 

 forms alloys with them, some of which are of great impor- ^ 

 tance. The amalgam of mercury with tin is used in silver- 

 ing mirrors. Pewter, which was formerly much used, is an ^ 

 alloy of tin and lead. In tinning iron the plates are immers- * 

 ed in the melted tin, and are either moved about in the li- 

 quid metal, or are dipped several different times. They are 

 then taken out, and rubbed to remove the impurities from 

 the surface. Tin is consumed in large quantities by the 

 dyers. It is employed to give a brightness to several articles 

 used in forming reds and scarlets. Substances which pro- 

 duced to the ancients only faint and fleeting colours, give us 

 such as are brilliant and durable, by the use of a solution of 

 this metal. 



Questions. — 1. What is said of the utility of iron ? 2. Of its 

 abundance ? 3. Of its oxyds ? 4. Of its sulphuret ? 5. How may an 

 artificial volcano be produced ? 5. How do you account for this ? 7. 

 What is green vitriol and prussian blue ? 8. Describe tin. 9. What 

 is said of the alloys of tin .'' 10. Of tinning iron plates .'' 11. Of the 

 use of tin by dyers ? 



LESSON 82. 



Zinc, Manganese, and Antimony. 



Sublima'tion, a process whereby certain volatile substances are 

 raised by heat, and again condensed by cold into a solid form : 

 thus are obtained flowers of arsenic and flowers of sulphur. 



Zinc is a very combustible metal, and when broken, ap- 

 pears of a shining bluish white. It is one of the most abun- 

 dant metals in nature except iron, and in Wales its ore was 

 employed till lately in mending the roads. It is used in 



