APPARATUS, MATERIAL, AND REAGENTS. 



633 



by means of a gas-pressure regulator ; (2) that the height of the watc r 

 in the tube is controlled daily by the 

 withdrawal or addition of a few drops of 

 distilled water ; and (3) that the apparatus 

 is kept in a place with as even a tempera- 

 ture as possible, and sheltered from currents 

 of air. 



The burners in Fig. 264 are protected 

 with mica cylinders similar to the burner 

 represented in Fig. 266. The flames of 

 these burners can be turned down to the 

 smallest length without danger of extinction, 

 and the temperature may be regulated very 

 satisfactorily without using the heat-regulator 

 just described, if the gas first passes through 



a pressure-regulator (Fig. 269). To provide FlG - 2GG. GAS-BURNER 

 against the danger resulting from accidental 

 extinction of the gas, Koch has devised a 

 self-acting apparatus (Fig. 267), which, simultaneously with the extinction 

 of the flame of the burner, shuts off the supply of gas. 





FIG. 267. KOCH'S SAFETY BURNER. 



Babes' Incubator. The pattern used by Babes is a very 

 simple one, and may be recommended for economy and efficiency 

 (Fig. 268). 



It consists of a double-walled chest with sides and roof jacketed 

 with felt. Water fills the interspace between the walls, and on 

 the roof are two apertures one for a gas-regulator and the other 



