of the Fixed Oils in contact with Sulphur. 



165 



glass balloon, to the mouth of which two tubes were adapted, 

 one descending to near the middle, and furnished with a cork 



at the upper end, the other which constituted the neck of the 

 distilling apparatus passed into a tubulated receiver, kept cold 

 by immersion in water or ice. To the tubulature, a doubly 

 bent tube was affixed, which descended into a vessel of alcohol, 

 for the purpose of retaining any of the more volatile portions 

 which might be carried over by the rapid current of sulphu- 

 retted hydrogen. The heat must be applied by means of an 

 open charcoal fire ; and the furnace should be so constructed 

 that the fire may be rapidly withdrawn in the event of the 

 action becoming too violent. It is very desirable too that the 

 balloon should go down into the furnace, so that it may be 

 entirely surrounded by hot air. The oil is introduced into 

 the balloon, of which it must not occupy more than a fifth, or 

 a fourth at most, along with a few small pieces of sulphur, and 

 heat is gradually applied. So soon as effervescence com- 

 mences, the cork of the small tube is withdrawn, and a small 

 piece of sulphur is introduced ; and this is continued gradually, 

 so as to keep up a uniform action. A dark reddish-brown 

 oil passes into the receiver, and at the same time sulphuretted 

 hydrogen passes in torrents through the alcohol ; it there 

 deposits a certain quantity of oil, and on escaping, may be 

 kept burning during the whole operation, with a flame eight 

 or nine inches high. The principal difficulty of this process 

 consists in regulating the heat, so as to keep up a steady action. 

 If the heat be allowed to fall, the contents of the balloon be- 

 come so viscid as inevitably to boil over ; and at the same time 

 too high a temperature causes the whole action to go on with 



