Prof. Regnault on the Specific Heat of some Simple Bodies. 105 



stationary temperatures, very different from 100° .may be obtained 

 in the bath. With bisulphide of carbon the temperature is 46°; 

 with chloroform 60° ; with alcohol 78° ; with oil of turpentine it 

 is 157°, &c. It is even easy to obtain in the bath a stationary 

 temperature perfectly fixed beforehand ; for this purpose it is 

 sufficient to place in the boiler V a liquid whose temperature 

 under the ordinary atmospheric pressure is very little different 

 from that desired in the bath, and then to boil this liquid under 

 a pressure either greater or less than that of the atmosphere, so 

 that the thermometer exactly indicates the desired temperature. 

 In this case the tube h i is connected by means of a leaden pipe, 

 with an air-reservoir, the pressure of which may be varied at 

 pleasure by a suction or forcing-pump. 



I shall not revert to the method of conducting these experi- 

 ments ; it has already been sufficiently described in my previous 

 memoirs. 



When it is desired to determine the specific heat of a body 

 which liquefies or even softens much at temperatures slightly 

 above that of the surrounding air, it cannot be heated in the 

 bath, and recourse must be had to the inverse method, which 

 consists in cooling the body in a cooling mixture, and determi- 

 ning the fall of temperature which it produces by its immersion 

 in the calorimeter. I have described (Ann. de Chim. et de Phys. 

 vol. xlvi. p. 270*) the apparatus I used for this purpose. This 

 apparatus I have replaced by another, easier of manipulation, 

 and by which the temperature can be better regulated. The 

 cold is produced by the evaporation of a very volatile liquid in a 

 continuous current of air, which can be regulated at will: fig. 2, 

 Plate II. represents its vertical section. In a central tube A, 

 like that in fig. ], and provided at both ends with the same 

 stoppers, is placed the basket M containing the substance 

 whose specific heat is to be determined. It is surrounded by a 

 second tube 13 of the form shown in the figure, and which is her- 

 metically soldered above and below to the tube A. A third tube, 

 C, surrounds the two others, and forms a protection to the tube 

 B against immediate contact with the surrounding air, and pre- 

 vents the deposition of dew. 



On the upper circular base of the tube B are two tubulures; 

 on one of which is soldered the trifurcate tube bade; through 

 the other a bent tube efg passes, provided with a stopcock ?-, and 

 which descends to the bottom of the tube B. The whole system 

 is placed on a support provided with screws, like that in fig. 1. 



The volatile liquid, ether or bisulphide of carbon, is poured 

 into the tube B through the orifice d, which is then closed. In 

 order that the level of the liquid may not sink below hi in con- 

 * Phil. Mag. vol. xii. p. 498. 



