CLEAR FUSED QUARTZ MADE IN THE ELECTRIC 



FURNACE 1 



By Edward R. Berry, D. Sc. 

 Thomson Research Laboratory, General Electric Co. 



[With 3 plates] 

 INTRODUCTION 



It is the purpose of this article to present some of the recent re- 

 sults of the development of clear fused quartz and to focus atten- 

 tion on some of the surprising properties of this material. The art 

 of making fused quartz dates back to 1839 when Gaudin, in France, 

 discovered the general thermal properties of fused quartz. A num- 

 ber of advances have been made in the art since that date by various 

 investigators; but most of this work has been concerned with the 

 opaque variety of fused quartz usually made from sand. It is only 

 during the past 23 years that the development of clear fused quartz 

 has made very rapid progress. 



It has been possible for many years to make fused quartz of a 

 high quality in small sections and lengths by hand labor in the 

 ordinary blast flame, using gas and oxygen. This has been done by 

 piecing together small sections of crystal in the flame; or by adding 

 silica powder from time to time until the piece has grown to the 

 heating limit of the flame, an obviously slow and expensive process. 

 From this step in the development of the art to the point where 

 very large masses of equal qualit}'^ can be made has been a long and 

 difficult one. In the last few years the advances made by the process 

 described in this article have been so rapid and far-reaching that 

 there seems to be no limit now to the size of high-quality clear fused 

 quartz which can be made, except that which may be imposed by 

 mechanical difficulties. 



METHOD OF FUSION 



When it is desired to obtain fused quartz of the quality which is 

 illustrated in this article, it is necessary to start with the very 



^ Presented at the forty-flfth meeting of the American Electrochemical Society at Phila- 

 delphia, Apr., 1924. Reprinted by permission from the General Electric Review, 

 June, 1924. 



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