ILLUMTNANTS 7 



dissolver is in good order. Never jerk the dissolver when using large bore nipples or 

 jets with large mixing-chambers. Always move the handle slowly at first, but as 

 quickly as you like after. 



9. — Remember that you do not always get a strong light by turning on a large 

 quantity of the gases. The mixture must be correct to get a perfect white light. 

 There should be no hydrogen flame round the lime as with a blow- through. It is 

 this flame that gives trouble with the heat. 



The Gwyer Jet does not give a strong light by a larger consumption of gas, but 

 through the more perfect mixture and adjustment of the gases. 



10. — Keep the jet nipple clean and bright, and if your jet has a tendency to roar 

 or hiss send it to the works to be tested. A very small accident will sometimes 

 prevent the smooth working of a jet, and which generally takes only a few minutes 

 to remedy. It is very rarely that any charge is made for repairs of this sort. 



1 1. — The No. I and 2 jets are generally sent out with a tV inch bore nipple, but 

 when not working to the full power a inch bore may be used with advantage, and a 

 lime of f inch diameter. 



1 2. — The size bore of the nipple should be in proportion to the light required if the 

 jet is to be worked to the best advantage. A whiter light will be obtained with a 

 mch bore at full pressure than a tV inch at half pressure, each consuming approximately 

 the same quantity of oxygen. The lime also should be proportional to the amount 

 of light : a small lime will give the best result with a small bore nipple." 



Fig. 4a 



The Blow-through Jet (Fig. 4A).-This form is the easier one to work, and to 

 those commencing the safest. It consists of two tubes to which the oxygen and coal 

 gas are respectively attached by india-rubber tubing. The coal gas is lighted first 

 and the oxygen then turned on, which "blows through" the stream of coal gas, and 

 then is made to impinge on the lime. Too much oxygen will blow out the coal gas, 

 too little will give but a feeble light. 



Whichever jet be used the oxygen must always be under pressure, and if the 



