Glass Working Bending and Blowing 79 



with camphorated turpentine. A badly fitting burette stopper 

 or the stopper of a reagent or other bottle may be ground 

 to a good fit by moistening with a thin paste of flour emery, 

 and camphorated turpentine by inserting the stopper with a 

 twisting motion and working backwards and forwards. It 

 should be frequently removed, and reinserted at a different 

 place, and this process should be continued, plenty of the 

 emery-camphor-turpentine mixture being used until the cleaned 

 stopper fits accurately without rocking. The ground surfaces 

 must be well washed before use. Burette stoppers should be 

 greased with special grease, as recommended in Section IV. 



SUB-SECTION (B) 

 BENDING AND BLOWING 



I. MATERIAL 



THE glass used in glass blowing is either " lead glass " 

 or "soft, soda-glass." Magnesia or other glass is too hard 

 to work comfortably in an ordinary flame, and such work 

 as may have to be done upon it demands the use of the 

 oxy-gas flame, which will be treated of later. Ordinary 

 "hard" or "combustion" glass may be worked, though with 

 difficulty, in an ordinary blowpipe flame, but it would be a 

 misnomer to call such working " blowing." Hence we are 

 driven to deal only with soda-glass work, in this section, lead 

 glass being very little used nowadays. 



The glass is made in practically all the usual sizes and 

 weights, consequently no difficulty will be experienced in 

 obtaining suitable material, though in ordering, it is well to 

 state specifically that the glass is for glass blowing. It may be 

 obtained from almost any dealer in scientific apparatus, but, 

 as it shows some tendency to perish or devitrify after some 

 time, it is well to secure a stock from some tradesman whose 

 stock is constantly moving. Messrs. Miiller Orme & Co., 

 148, High Holborn, may be relied upon in this way. 



Soda-glass is easily recognized when under treatment in 

 the blowpipe flame, but is not so easy to recognize while in 

 stock. Usually, however, its colour, looking at a tube endways, 



