73 
HALL 77. 
FICTILE iTATERIALS, ETC, 
Cases 1,5, and. 12. — Clays are the product of the decom- 
position of rocks containing feldspar ; for instance, granite and 
porphry. Kaolin is one of the purest of the clays and is non-plastic 
when washed. 
The uses of clay making materials are generally as follows : • 
1. Domestic — Utensils, porcelain ware, and earthen ware. 
2. Structural — Brick, common front or pressed, ornamental, 
hollow, glazed, terra cotta, roofing tile, drain tile, flooring tile, fire- 
place tile, chimney flues, chimney pots. 
3. Hydraulic Structures — Water conduits, reservoir liniiigs, 
sewer pipe. 
4. Industrial A rts — China clay, chemists’ crucibles, and other 
♦apparatus, wall and writing paper filling, refractory clay, lime and 
cement. 
5. Ornamental and ^Esthetic uses — Tile, ornamental pottery, 
terra cotta decorations, artists’ moulding clay. 
6. Djiitative — Food adulterant ; paint adulterant. 
ALUMINIUM. 
Case 10 . — The minerals from which aluminium is obtained 
are Bauxite, found abundantly in Georgia, and Cryolite in Green- 
land. By chemical treatment of the minerals, and subsequent 
electric smelting of oxide of alumina the metal is liberated. 
Aluminium forms alloys with gold, copper, steel, and other metals, 
some of the alloys possessing very useful properties. 
Cases 2 and 4. — Assayer’s crucibles, muffles, etc. 
3. — Pottery. 
Case 6. — Fancy brick. 
Cases 7 and O. — Tripolite and its application. 
8. — A giant muffle and exhibit of sewer pipe. 
Xo. 11. — Cement materials, made mainly of Portland 
cement. 
No. 13. — ^Terra cotta materials. 
