1 52 [ASSEMBLT 



has been made malleable. It naturally absorbs a portion of 

 light — in one form, it polarizes light — as a lens, it refracts it j. 

 with a polished surface, it reflects it — in the form of a prism, it 

 decomposes it. The refracting power of glass is said to be ia 

 exact proportion to its density. It transmits nearly all the heat 

 of the sun's rays, but refuses to transmit the artificial heat of 

 ordinary fires, detaining or absorbing the whole of it. 



It resists all the acids except the fluoric, by which it may be 

 dissolved at common temperatures. It may be easily drilled if 

 the drilling tool be lubricated with camphorated spirits of tur- 

 pentine. Bells have been made of glass in Sweden, which rival 

 those made of metal in power and sweetness of tone. Flutes and 

 other musical instruments have also been made of it. Glass may 

 be drawn into fine threads and woven with silk so as to produce 

 the most beautiful fabrics. It is electric by friction, but a very 

 imperfect conductor of electricity. If large quantities of electri- 

 city are made to pass through it, the glass is reduced to powder 

 by the shock. It melts at 10.179° F., or TO'' Wedgewood ; will 

 expand the TiVitli ^^ its length by raising its temperature from 

 ^2° to 212° F. 



Nature elaborates a substance nearly, if not quite resembling 

 glass, and uses it for the preservation of a variety of plants ; for 

 instance, bamboo, rattan, the stalks of Indian corn, wheat, rye, 

 oats, barley, rice, the sugar cane, &c., are all covered with a 

 thin coat of silica, which renders them impervious to water. 



It would be difficult to compute the value of glass, looking 

 alone to the aid which science has derived from it. It is only 

 about 240 years since Gallileo first discovered the satellites of 

 Jupiter, through the aid of a rude and very imperfectly con- 

 structed telescope. The immense advances which the science of 

 astronomy has since made, so vastly important to the pursuits of 

 life, have been mainly through aid derived from the material of 

 glass. 



It is about sixty years since glass was first manufactured in the 

 United States. The first establishment was erected in Boston for 

 making window glass. The business has advanced to a very 



