PART III 



CHAPTER I 



DESCRIPTION OF THE INSTRUMENTS, REAGENTS, AND 

 CHEMICAL TESTS USED IN THE BLOWPIPE TABLE 

 FOR THE DETERMINATION OF THE MINERAL SPE- 

 CIES 



VERY little apparatus and few reagents are necessary for the 

 blowpipe determination of the common minerals. While elab- 

 orate apparatus and mechanical blowpipes 

 have been devised, equally as good results 

 can be obtained by the careful worker with 

 but few and very simple instruments ; the success 

 of blowpipe work will depend upon the care and 

 skill of the worker rather than upon the elaborate- 

 ness of the instruments used. 



The blowpipe is by far the most important of all 

 the instruments required. It is in constant use 

 and takes part in almost every experiment. The 

 style of blowpipe to be recommended is that known 

 as the Freiberg model, Fig. 524. This model pos- 

 sesses a trumpet mouthpiece, either of hard rubber 

 or horn, with which blowing may be continued for 

 a long time with very little, if any, fatigue. A 

 trumpet mouthpiece is not necessary, but it in- 

 volves considerable muscular energy to keep the 

 lips closed around a tube inserted in the mouth, 

 with the necessary air pressure on the cheeks, 

 to yield a strong and constant blast. Where both 

 kinds of mouthpieces have been used there will 

 never be any doubt that the trumpet style will be 

 the one chosen. The shaft B may vary in length 

 according to the desire and convenience of the 

 individual, but as manufactured it is about 23 

 cm. long. Freiberg blowpipes are fitted with plati- 

 num tips; this is expensive, but necessary where 

 much work is to be done. Some dealers furnish a 

 spun tip, which is always very thin at the point, so 

 FIG. 524. 546 



