THE LI ME- LIGHT 51 



the lime- turning movements presently described can be 

 applied to them. 



The jets next treated of can, with care, be also used as 

 oxy-gas jets, as by-and-by mentioned. 



29. The Mixed-gas Jet This term is often abbreviated 

 into ' mixed ' jet, and signifies that the two gases are actually 

 mixed in proper proportions before combustion at the orifice ; 

 for in this jet there is but one, to which both gases in a mixed 

 state are conveyed. It gives the most powerful and whitest 

 light, in a smaller space ; and is easily reduced to any degree 

 desired ; and for the same amount of light, uses less gas. It 

 is, therefore, the form used in first-class lantern exhibitions, 

 and gives far the most brilliant results in optical and physical 

 experiments, while for high microscopic powers it is indis- 

 pensable. There is a widespread notion that it is ' liable to 

 explosion,' which has been partly fostered by the errors of 

 opticians, and their mistaken so-called ' safety ' arrangements. 

 But the conditions of safety are now well understood ; and 

 while it is not a jet to be trusted if, indeed, any jet ought to 

 be to the manipulation of clodhoppers, schoolboys, or absolute 

 novices, with those who understand it the mixed jet is the 

 most simple to manage and easy to control of any, and 

 perfectly safe. 



Both gases have to be used under approximately equal 

 pressure, and the first arrangement employed was to mix pure 

 hydrogen and oxygen, in the proper combining proportions, 

 in one vessel, expelling the mixed gas through a minute 

 orifice. It is often stated that this method gives the most 

 brilliant light. That is a total mistake. No light was ever 

 obtained in those days nearly equal to what is obtained now ; 

 while the mistake led to a series of explosions which it was 

 impossible to prevent with any certainty, and which gave the 

 mixed-jet a bad character. Mr. Newman used a nipple of 

 one-eightieth of an inch bore with success for some time ; 

 but directly he changed it for one slightly larger about 



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