THE LI ME- LIGHT 71 



far it may be possible to supply such material ; but as the 

 subject has occupied my own attention for years, and has also 

 interested others, I have thought it better to give, however 

 briefly and imperfectly, the very latest information I have 

 regarding it. 



37. Management. We will now suppose the two bags 

 full, and all apparatus ready at hand. The first step is to 

 place the bags in the boards, and it is best to place the oxygen 

 at the bottom. This is the direct opposite of the usual 

 direction, but I am certain of its correctness. It ensures a 

 shade more weight (that of the top bag and board) on the 

 oxygen, and the result is, that if any change in adjustment 

 of the gases does take place unnoticed, it will probably be 

 in the direction of too much oxygen, which will snap the jet, 

 put the light out, and so give notice. Then the weights are 

 placed on, and if necessary tied on, the vulcanised tubes con- 

 nected with the jet-nozzles (dissolving and cut-off taps will 

 be described in Chapter VIII.), and both taps of the jet turned 

 off. Generally the two taps will be different colours, or one 

 will have a hole through the thumb handle ; if not, care 

 should be taken that the same side be always used for the 

 oxygen, in order that the hand may always go to the proper 

 tap by instinct. 



A lime should now be placed upon the pin, first clearing 

 out the hole from dust by turning a match round in it, 

 and wiping off all loose pow- 

 der by a good rub with the 

 tissue-paper in which it 

 was wrapped. For handling 

 limes, and especially for re- no. 45. Lime-tongs 



moving a used-up or cracked 



one, the lime- tongs shown in fig. 45, made by bending a strip 

 of sheet- brass, will be found very convenient. 



Both bag-taps are now turned on, and the hydrogen jet- 

 tap may be turned on a little and lighted, giving flame enough 



