CH. IV] MAGIC LANTERN WITH THE LIME LIGHT 105 



burners they are placed on a pin or axle, and then must have a 

 corresponding central hole. With other burners they are pressed 

 into place between surrounding springs, somewhat as a lamp 

 chimney is put on its burner (fig. 57, 59). 



The limes are sealed hermetically in glass tubes, or are packed in 

 powdered unslaked lime, in air-tight tin cans, to prevent the access 

 of moisture. 



If moisture reaches the limes they will slake and become powdery 

 and useless for the light. To avoid any moisture reaching them 

 they should not be removed from their protective covering until a 

 few minutes before they are to be used. 



158. Lamp for the lime light. This consists of a burner or jet 

 for conducting the two gases, oxygen and hydrogen, to a point 

 where they can be mixed and burned ; and a device for holding the 

 lime in a proper position, and raising, lowering, rotating and adjust- 

 ing the lime with reference to the burner. 



There are two principal forms of burner or jet : 



(1) The blow-through jet. In this a stream of oxygen is blown 

 into a flame of hydrogen on the principle of the gas or alcohol blow- 

 pipe (fig. 58). 



(2) Mixed jet. In this form the two gases (oxygen and hydro- 

 gen) meet and mix in a common chamber just before the nozzle 



H O H O HO 



FIG. 58. FORMS OF BLOW-THROUGH JETS (Lewis Wright). 



The form c shows best that the principle is that of a blowpipe. 



The form d approaches the mixed jet somewhat. 



With all of them the hydrogen, or hydrogen substitute (illuminating gas, 

 ether or gasoline vapor) passes out from the supply through the tube marked 

 H at the left. The oxygen is then blow r n through the flame from the tube at 

 the right marked 0. Not so much light can be got with these jets as with the 

 mixed jet, but for illuminating gas or ether vapor, etc., this form, especially 

 a, b, c is safer in the hands of amateurs than the mixed jet. 



