Manchester Memoirs, Vol. xlvi. (1902), No. C 5 



thick-walled tubes of quartz, with a core of about }i inch. 

 As seen from the figure, a rough mould was made of 

 carbon with a carbon core, resting at each end on carbon 

 supports. The mould was arranged usually for making 

 tubes 10-12 inches long, but, obviously, any desired 

 length of tube could be similarly constructed. The 

 mould was filled \\\\\\ broken-up quartz of different 

 degrees of fineness, but it was found that the best results 

 were obtained when the quartz was not too finely 

 powdered. The tubes obtained in this way can easily be 

 separated from the carbon support and the core be with- 

 drawn, since the silica does not adhere to the carbon. 



Up to the present, I have not succeeded in preparing 

 tubes quite free from bubbles, but the general appearance 

 can be greatly improved by re-heating under the arc, 

 preferably with mechanical rotation in order to get a 

 more uniform result. Even in their present form, however, 

 they would probably be of much use for constructing 

 apparatus, as, owing to their thickness, there is plenty of 

 material for blowing and drawing down purposes, and by 

 this process the appearance of the material is, of course, 

 much improved. 



Pure white sand fused in a similar way always seems 

 to give a much more opaque mass ; but plastic quartz 

 can take up a certain amount of sand without thereby 

 impairing its transparency, and probably a small sand 

 blast, blowing sand or fine quartz, could be used for 

 thickening bulbs and tubes of quartz fused by this method. 



It is to be hoped that those who have large power at 

 their disposal will extend the application of this method, 

 which may thus bring fused quartz apparatus within the 

 reach of those wishing to make use of it in virtue of its 

 interesting and valuable properties. 



The experiments described in this paper were carried 

 out in the Physical Laboratories at Owens College. 



