FAVRE AND SILBERMANN'S CALORIMETER. 21 



The oxygen passed into the calorimeter by a copper tube 

 opening at one of the sides of the box near the bottom. 

 The gases of combustion were drawn into a gas-holder. The 

 apparatus was enclosed in another likewise rectangular, in 

 which was put 1 1 litres (9! quarts) of water. This was the 

 calorimetric cylinder. The water was kept in motion by an 

 agitator. 



The unit chosen by Dulong was one gram of water whose 

 temperature was raised one degree. He corrected the tem- 

 perature observed, same as Rumford, but he also noticed 

 that this correction was correct only when the first period 

 was equal to the second. The results obtained by Dulong in 

 1838 were not published till after his death, in 1843. For 

 hydrogen and carbonic oxide they are but slightly different 

 from the most modern determinations. 



CALORIMETER OF FAVRE AND SILBERMANN. 



In 1852 Favre and Silbermann published their first 

 researches on the quantities of heat generated by chemical 

 action and described their calorimeter. 



All rapid-combustion calorimeters and all with constant 

 pressure intended for solid bodies are copied more or less after 

 that of Favre and Silbermann. The principle and mode of 

 execution in their general lines are the same; the form in some 

 details or the material employed for the combustion-chamber 

 has been modified more or less; but the general apparatus 

 and accessories, as well as the method, have remained as 

 F. & S. left them. We will describe, then, this calorimeter 

 in its details, and outline the modifications made by other 

 experimenters. 



The calorimeter called Favre and Silbermann's is composed 

 of three concentric copper cylinders (Fig. 2, B, C, D). 

 Cylinder B is the calorimeter cylinder; it is silver-plated and 

 polished on the inner surface so as to lessen its emitting 

 power; its capacity is a little over 2 litres (3^- pints), being 20 



