272 SEC. 8. HEAT. 



adjustment, with two pointers, is used to take, by means of the cathetomtter, 

 the height of the mercury in the small glass vessel which is placed underneath 

 the apparatus. Above is arranged a glass cylinder which serves to hold the 

 ice in the experiment. A bent tube lets the water which runs off escape. 



lO58f. Regnault's Apparatus for determining Specific 

 Heat of Liquids. L. Golaz, Paris. 



This apparatus consists of a cylindrical copper vessel, having at its lower 

 extremity a lateral conical appendage. In the axis of the vessel there is a 

 cylinder of brass which receives the liquid to be experimented upon, and which 

 is furnished at its upper part with a vertical tube, into which is inserted a 

 thermometer, giving the temperature of the liquid. The cylinder terminates 

 .in a stop-cock inclined downwards, and having at its lower extremity a tube 

 which, after having traversed the conical space, is soldered to the cylinder, 

 enters the tube of the calorimeter at the other side of the stop-cock, and 

 terminates in a tube which goes through the wall of the cylinder. It is by 

 this tube that the key of this stop-cock enters, it being worked from the 

 exterior. A hole made in the hand of the key establishes a current of air 

 which drives the liquid into the calorimeter, at the same time that the stop- 

 cock is turned for that purpose. 



A double wooden screen, fixed perpendicularly, cuts off all radiation from 

 the vessel which is being heated or from the calorimeter. Two iron arms 

 fixed to the upright of the screen support the vessel at such a height that a 

 gas burner may be placed underneath. 



The calorimeter consists of a brass cylinder, into which passes the liquid 

 experimented on, and of a flat vessel containing a thin screw- shaped blade 

 for the purpose of condensing the vapour which might be generated by the 

 liquid in the vessel. A brass receptacle surrounds this first calorimeter, 

 a second one, resting upon feet made of wood or cork, surrounds the first. 

 The height and the position which must be given to the calorimeter are regu- 

 lated by a stand with a movable column. The description of the experiments 

 with this instrument is to be found in " Memoire de 1' Academic," tome 26, 

 page 262. 



This apparatus is constructed of glass, copper, or platinum, according to 

 the nature of the liquids upon which it is desired to operate. The one exhi- 

 bited is made of platinum. 



1058g. Favre's Mercury Calorimeter. 



L. Golaz. Paris. 



This apparatus consists of a large spherical reservoir of cast-iron, resting 

 on a support of iron, surrounded with a non-conducting substance. Under- 

 neath is made a vertical opening, through which a steel piston passes, being 

 set in motion by a screw provided with a winch-handle. Near the centre of 

 the sphere there is a cast-iron tube on which is screwed a steel stop-cock, 

 terminating in a small glass ball, to which is fitted a carefully calibrated 

 horizontal thermometer. The graduations on the stem of this thermometer 

 correspond with its interior capacity ; it is supported by two wooden columns, 

 which rest upon a solid bench opposite the stem, and on the corresponding 

 side are two iron tubes, placed obliquely with regard to the vertical diameter 

 of the sphere. These two tubes, called "mouffies," are immovably fixed to 

 the iron sphere, and extend to its interior. They are thus completely sur- 

 rounded with mercury when the reservoir is full, an operation which is very 

 easily accomplished by means of two stop-cocks placed opposite to the 

 plunger. A small glass pipe of a particular shape is used for bringing liquids 



