Some Experiments on the Latent Heat of Steam. 51 



end. By governing the gas supply to the burner under 

 the boiler with a Moitessier's glycerine gas-regulator, the 

 rate of boiling could be kept constant. Also the pressure 

 under which the water boiled could be adjusted to any- 

 thing up to 1,300 mm., by connecting the receiver in 

 which the steam from the jacket condensed, with a large 

 vessel provided with a manometer, a small compression 

 pump, and a Staedel's pressure regulator. By this regulator 

 the pressure could easily be kept constant to within "5 mm. 

 of mercury. 



Since for the new apparatus a larger supply of steam 

 was necessary than for the earlier experiments, it occurred 

 to me that by superheating the steam from an ordinary 

 boiler strongly, then reducing its temperature to a few 

 degrees above the boiling point, I should be able to get 

 rid of any particles of water which might possibly be 

 carried over, and at the same time, by measuring the 

 temperature of the steam just before it entered the 

 calorimeter, have a guarantee that no condensation had 

 occurred on the way, since it seems extremely improbable 

 that even very slightly superheated steam should contain 

 liquid particles. 



The steam was generated in a flat-shaped copper 

 boiler, heated as uniformly as possible over its lower 

 surface by a ring burner. From this it passed to the 

 superheater, which consisted of a long coil of solid drawn 

 copper pipe placed in a horizontal furnace on the principle 

 described by Lothar Meyer (Ber. Deutsch. Client. Ges., 

 16a, 1087). Beyond the furnace was a wider tube in which 

 was a thermometer giving the temperature to which the 

 steam had been superheated. It then passed through the 

 salt-bath, which consisted of a vertical cylinder of stout 

 copper, through the walls of which was fastened a coil of 

 6 — 7 metres of copper pipe, surrounded by a salt solution 

 boiling at 103 . A reversed condenser prevented the con- 



