The fireside university of modern invention, discovery, industry and art for home circle study and entertainment . Calcium, lead, barium, strontium, magnesium,aluminium, zinc, or thallium. (For colored Glass): Iron, manga-nese, copper, chromium, uranium, cobalt, arsenic, or gold. Inbrief, Glass is a silicate or borate of at least two metals, and oneof these metals must be an alkali. The molecule of Glass maybe theorized, in the most simple manner, as three oxygen mole-cules, each one holding a molecule respectively of sodium (orpotassium), of calcium, and of silicon (or boron)—that is, soda(or
The fireside university of modern invention, discovery, industry and art for home circle study and entertainment . Calcium, lead, barium, strontium, magnesium,aluminium, zinc, or thallium. (For colored Glass): Iron, manga-nese, copper, chromium, uranium, cobalt, arsenic, or gold. Inbrief, Glass is a silicate or borate of at least two metals, and oneof these metals must be an alkali. The molecule of Glass maybe theorized, in the most simple manner, as three oxygen mole-cules, each one holding a molecule respectively of sodium (orpotassium), of calcium, and of silicon (or boron)—that is, soda(or potash), lime and sand (or borax, which also has soda in it).(See Chemistry.) 421 4*2 THE FIRESIDE UNIVERSITY. Illicit is required for Glass-making? A very great heat, and as most Glass articles are small, theGlass furnace is often divided into small pots or and Stevenson invented tank furnaces, to do away withthe little pots, but each plan has its advocates. Usually, a Glassfactory—as at the Worlds Fair of 1893—is a tent-like structure,in which the tall chimney is the Fig. 162. FASHIONING GLASS SHADES. How is this Glass bowl made ? A man gathers molten Glass on a rod and holds it over the GLASS. 423 mold; the pressman clips off the hot metal with shears; themass drops into the mold; the mold is shut and pressed andthe bowl is taken out, still red hot. It can now be furtherheated, wrought with a block of wood, and is cooled in a temper-ing oven. How are the molds made ? They are of iron, jointed in many places, so that they can beopened without breaking the Glass. When a vase or pitcheris smaller at the top than some part of its interior, it has beenwrought with the wooden block; ory it has been moldedanother way.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectscience, bookyear1902
