THE BOOK OF THE LANTERN. 77 



recommend the employment of two different kinds of 

 tubing. There is a hard black kind, made, I fancy, in 

 France, but easily procurable in this country, which wears 

 extremely well, far better, indeed, than the ordinary grey 

 kind. It is cheap as well as good. The only part where 

 it seems to deteriorate is the end, where it is being 

 constantly fitted on to the metal jet. This gets soft and 

 rough after some time, a failing which is easily remedied 

 by judicious amputation. Use for each gas a sufficient 

 length of this black tubing, and firmly attach to the end 

 of each piece a short length of the more elastic red tubing, 

 by which connexion with the bottle and house gas respec- 

 tively can be easily made. In joining the two kinds of 

 tubing together, use a couple of inches of lead pipe as a 

 connecting link between them. First draw the black 

 tubing half way over the lead, and then, if possible, allow 

 the red tube to cover both, securing the whole with 

 string. , - 



Having all these things ready, the H tube fastened to 

 the nearest gas supply, and the tube to the bottle or bag, 

 we can proceed to work. Let the lime-pin be so adjusted 

 that the lime is about 1-1 6th of an inch from the nozzle of 

 the jet. Then turn on the tap marked H, and light the 

 jet. Turn down the gas until the flame is about one 

 inch high, and let matters thus remain for five minutes, to 

 give the lime time to warm through. Without this pre- 

 caution, and if the oxygen is turned on at once, the lime 

 is apt to split up from the sudden heat. 



After this five minutes' rest, you may attend to the 

 oxygen supply. If the gas is supplied from a bottle or 



