104' Prof. Regnault on the Specific Heat of seme Simple Bodies. 



tagcously modified the bath which 1 employed for raising the body 

 to a temperature near 100°, inasmuch as I have substituted for 

 the charcoal fire by which the water in a boiler was kept boiling, 

 a gas-lamp which effects the same purpose, and does not require 

 the presence of the operator. 



The substance submitted to experiment is usually placed in a 

 brass wire-gauze basket M, provided on the inside with a cylinder 

 of brass-foil, in which is fitted the bulb of the thermometer T 

 which marks the temperature of the substance. This basket is 

 suspended by a silk thread, which traverses a hollow metallic 

 stopper R. The thermometer T is inserted in a stopper to 

 such a depth that the division 100 degrees only projects above 

 the bath by about a centimetre. 



The hot bath consists of three concentric envelopes. The 

 internal cylinder A, in which is arranged the basket and the 

 thermometer, is soldered hermetically both at the top and the 

 bottom to the external envelope. Its upper orifice is closed by 

 the stopper R ; its lower orifice by a slide m, so long as the 

 basket with its contents is being heated. Between the external 

 envelope C and the cylinder A, there is an intermediate envelope 

 fixed to the superior lid, and reaching below to the conical part 

 of the external envelope. The bath is supported by a wooden 

 stand DDP P', which acts besides as a screen in preventing the 

 radiation of heat on the calorimeter H, when this latter occupies 

 the place indicated in the figure (PI. II. fig. 1), at the instant 

 of immersing therein the heated basket. 



The boiler V communicates with the bath by a tube a b, which 

 traverses the intermediate envelope, and by which steam reaches 

 the annular space B B round the internal cylinder A. This 

 steam escapes by the apertures o o on the side opposite that 

 by which it enters. The steam descends by the external 

 annular space C C, and the condensed water re-enters the boiler 

 by the tube cd. The steam which has retained its gaseous state 

 passes from the bath by the tube e/into the larger tube G, ter- 

 minated above by a narrower tube hi, which is surrounded by 

 cold water continually renewed. The steam is completely con- 

 densed in this refrigerator, and returns to the boiler by the tube 

 kp : its temperature on so doing is very near 100°, for at G it 

 traverses the steam which is constantly coming from the bath. 



Ebullition is produced in the boiler V by means of a gas-lamp 

 W ; it goes on continuously without necessitating the presence of 

 the operator; the same quantity of water serves for an indefinite 

 period, for it always returns without loss to the boiler. This 

 new arrangement renders the operation very simple, and allows 

 the operator to proceed with other work. 



If the water in the boiler Vis replaced by other volatile liquids, 



