USE OF THE BLOWPIPE. 103 



stream of air, as long as is required. To effect this, the 

 beginner should first learn to breathe through the nostrils, 

 keeping the mouth shut ; next let him distend the cheeks 

 with the air thus inhaled, and make several respirations 

 without allowing the air to escape from his mouth ; when 

 able to effect this, let him put a blowpipe between his 

 lips, and filling his mouth with air, expel it, gently and 

 steadily, by the action of the cheeks, while he breathes by 

 his nostrils, applying the tongue to the palate, so as to inter- 

 rupt, in some degree, the communication between the mouth 

 and the nostrils. As the air in the mouth becomes exhausted, 

 it may be renewed by withdrawing the tongue from the palate, 

 and replacing it again, as in pronouncing the syllable tut. Let 

 him first practise this with the blowpipe alone, without apply- 

 ing it to a flame at all ; next let him try to keep up a flame 

 without directing it to any object; and lastly, let him 

 attempt to oxidise some of the metals, to reduce some of the 

 most facile ores, and to fuse some of the most fusible earthy 

 substances. Bismuth or galena will answer to begin with ; 

 and after practising with a few others, he may attempt the 

 various substances in the order prescribed in the treatise of 

 Mr. Griffin. 



As regards the flame, we should advise him to commence 

 with a candle : one of a substantial size and large wick is to 

 be preferred ; such as are called shoemakers' candles, with 

 double wicks, are extremely well adapted for the purpose. 

 As the candle, however, is apt to gutter from the heat of the 

 charcoal on which the mineral requires to be placed, the 

 student as he advances may use a tinned lamp, which may 

 be fed with oil, tallow, or naphtha. Alcohol is best, as 

 being clearest, and giving no smoke, but it is the most ex- 

 pensive. The wick of the lamp or candle, it may be added, 

 should be divided, to give a greater extent of flame, and 

 should be bent in the direction of the object to be ex- 

 amined. The orifice of the blowpipe should be held about 

 the tenth of an inch above the bent wick, and the air should 

 be impelled along the wick without touching it. The ope- 

 rator should place the candle in such a position as to be able 

 to rest both elbows on the table. It may be necessary to 

 add, that a gentle and steady blast is quite sufficient, and 

 that beginners commonly blow with too much violence. 



