84 



LABORATORY EXERCISES 



NOTE. Dr. J. C. Foye, in his " Handbook of Mineralogy," tells 

 how to make a home-made mouth blowpipe out of a clay pipe (Fig. 

 30, this manual). His method is given in modified form. A piece of 

 pipe stem about 5 cm. (2 in.) long is broken off, 

 and the hole in the smaller end is filled for a dis- 

 tance of about 1 cm. with putty. A fine needle 

 is pushed through the putty. The closed end of 

 the pipe stem is heated in a Bunsen flame until 

 the putty is hard; the needle is then pulled out. 

 There remains a small, smooth hole. 



The piece of pipe stem is fastened to the bowl 

 of the pipe by means of plaster of Paris. Cut 

 out of cardboard a circle that will just go into 

 the bowl of the pipe, make a hole in the center, 

 and push the piece of pipe stem through the hole. 

 Push the cardboard into the bowl, having the 

 prepared "tip" outward, and fill the bowl, above 

 the cardboard, with a thick paste of plaster of 

 Paris and water. When the plaster of Paris has 

 "set," the blowpipe is ready for use. 



a. Test the pieces of pyrite and hematite with a magnet. 

 Are they attracted? 



6. Break a small piece of pyrite into powder, and heat it on 

 charcoal, or on a piece of soft earthenware, in a blowpipe flame. 

 The method is as follows: 



With a pocket knife hollow out a depression near one end of the 

 piece of charcoal, and put the powdered pyrite into it. To make the 

 blowpipe flame we use a luminous gas flame about 4 cm. (1.5 in.) high. 

 Hold the charcoal in your left hand, and the -blowpipe in your right. 

 Place the tip of the blowpipe just at the outer edge of the flame at its 

 middle part, and blow a steady stream of air against the flame. Have 

 the tip turned slightly downward, so that the flame produced will be 

 forced down upon the pyrite. Hold the pyrite so that it will be at 

 about the middle of the long blowpipe flame. In using the blowpipe, 

 breathe regularly through your nostrils; your puffed-out cheeks should 



FIG. 30 



A Home-Made Mouth 

 Blowpipe. 



