96 PHOTOMICROGRAPHY 



through jet. The oxygen passes through the saturator 

 and carries ether vapour with it to the jet, and the mixture 

 of oxygen and ether frequently gives a better light than 

 oxygen and coal gas. The distance of the jet from the 

 lime is of importance, as if it is too far away the flame is 

 too large, if too close there is not sufficient light. Experi- 

 ence will soon indicate the best position to get a compact 

 light of great intensity the jet is usually between J and 

 I inch from the lime. The candle-power generally at- 

 tained varies from 500 to M)00, and with mixture 

 jets 1500 and more can be obtained. 



Fig. 28 



INJECTOR JET 



The " Injector jet," shown at Fig. 28, as made by 

 Messrs. Butcher, is constructed to combine the power of 

 the mixture jet with the economy in gas of the blow- 

 through. It has the appearance of a mixture jet, and 

 may be used as such when it is desired to get the greatest 

 amount of light from it. Under ordinary circumstances 

 one tube is connected with the oxygen cylinder, and the 

 oxygen enters the mixing chamber under pressure, there 

 to mix with coal gas entering through the other tube 

 from the main. 



Gas and Oil Lamps. Acetylene gives a small and very 

 actinic flame, but the intensity is not quite uniform over 

 its entire surface. The candle-power of an ordinary double 



