128 ELEMENTARY CHEMICAL MICROSCOPY 



ring with thumb-screw is substituted for the simple ring. This 

 wire ring is useful as a support when moderately long heating 

 must be practiced or when evaporations over a tiny flame at 

 moderate temperatures are required. 



For the production of higher temperatures than are possible 

 with the flame of the Bunsen burner, a blowpipe will be found 

 convenient. The usual form employed in the blowpipe analysis 

 provided with a platinum tip should be chosen and if in addition 

 it can be fitted with a hot blast attachment its usefulness will 

 thereby be greatly increased. 



FIG. 74. Type of Small Blast Lamp for Microchemical Analysis. 



Where the work table is supplied with compressed air a minia- 

 ture blast lamp of the type shown in Fig. 74 is an invaluable aid 

 in fusions, production of high temperatures, preparation of tiny 

 blown glass apparatus, etc. ; having two joints it can be quickly 

 adjusted to almost any position and can even be employed to 

 heat material directly under the microscope, although such oper- 

 ations are best performed by means of an electric current since 

 the heat may thus be far better localized. 



Heating preparations while subjecting them to observation 

 through the microscope may be accomplished by means of the 

 electrically heated hot stage (see page 224) or by a tiny flame 



