SCIENTIFIC DEVELOPMENTS IN THE 

 GLASS INDUSTRY 1 



BY DR. R. SCHALLEE 



THE manufacture of glass involves first the chemical 

 process of producing glass from the proper raw materials, 

 and secondly the mechanical art of fashioning the molten 

 glass into the multitude of articles for which the market 

 calls. The mechanical aspect of the industry was early 

 developed to a high state of perfection. It is only within 

 comparatively recent times, on the other hand, that the 

 chemistry of glass making has been worked out with scien- 

 tific method. The need for such a development first made 

 itself felt with special force in connection with the manu- 

 facture of optical instruments, and it is largely this cir- 

 cumstance which caused the famous Jena Glass Works to 

 undertake the systematic study of the physical and chem- 

 ical properties of glass. 



The influence of the composition of glass on its proper- 

 ties is best brought out by a graphic representation. Thus 

 in Fig. 1, distances measured off to the right, along the 

 axis of the abscissae, represent the composition of a soda 

 glass, while the corresponding ordinates represent tempera- 

 tures. The curve drawn out in a full line shows the upper 

 limiting temperature of devitrification. This means that 

 a soda glass of a given composition remains glassy provided 

 it is not cooled below that point on the curve, which cor- 

 responds to the particular composition of the glass. Thus 

 for example a glass containing about 75 per cent, of silica 

 (Si0 2 ) and 25 per cent, of soda (Na 2 0) can be cooled to 



Abstracted from a paper read before the Verein deutscher 

 Chemiker at Frankfort, a. M. From Scientific American Supplement 

 No. 1797, June, 1910. 



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