OF CENTRAL CANADA PART I. 23 



minerals from one another : some of these being fusible, whilst others 

 are infusible ; some attracting the magnet after exposure to the blow- 

 pipe, whilst others do not exhibit that reaction ; some imparting a 

 colour to the flame, others volatilizing, and so forth. Secondly, the 

 blowpipe may be employed to ascertain the general composition of a 

 mineral ; or the presence or absence of some particular substance, as 

 copper, lead, iron, cobalt, manganese, sulphur, arsenic, and the like. 

 Thirdly, it may be used to determine in certain special cases, the 

 actual amount of a metallic or other ingredient previously ascertained 

 to be present in the substance under examination. 



In using the blowpipe, the mouth is filled with air, and this is 

 forced gently but continuously down the tube by the compression of 

 the muscles of the cheeks and lips, breathing being carried on sim- 

 ultaneously by the nostrils. By a little practice this operation be- 

 comes exceedingly easy, especially in ordinary experiments, in which 

 the blast is rarely required to be kept up for more than fifteen or 

 twenty seconds at a time. The beginner will find it advisable to 

 restrict himself at first to the production of a steady continuous 

 flame, without seeking, to direct this on any object. Holding the 

 blowpipe in his right hand, (with thumb and two outside fingers 

 below, and the index and middle finger above the tube,) near the 

 lower extremity, he should let the inner part of his arm, between the 

 wrist and the elbow, rest against the edge of the table at which he 

 operates. The jet or point of the blow-pipe is. turned to the left, and 

 inserted either into or against the edge of the flame, according to the 

 nature of the operation, as explained below. After a few trials, when 

 sufficient skill to keep up a steady flame has been acquired, the point 

 of the flame may be directed upon a small splinter of some easily 

 fusible material, such as natrolite or lepidolite, held in a pair of for- 

 ceps with platinum tips.* Some little difficulty will probably be 

 experienced at first in keeping the test-fragment exactly at the flame's 

 point ; but this, arising partly from irregular blowing and partly from 

 the beginner being constrained to look at the jet of the blow-pipe 

 and the object simultaneously, is easily overcome by half-an-hour's 

 practice. A small cutting of metallic lead or particle of grey anti- 

 mony ore supported on a piece of well burnt soft-wood charcoal can 



* If forceps of this kind caunot be procured, a pair of steel forceps with fine points, such as 

 watchmakers use, may serve as a substitute. It will be advisable to twist some silk thread or 

 fine twine round the lower part of these in order to protect the fingers. The points must be 

 kept clean by a file. 



