534 Intelligence and Miscellaneous Articles. 



first approximation, which must be perfected bj-- a more profound 

 study and a more perfect knowledge of the phaenomena. 



I have commenced the study of the pliysical properties of bodies 

 with the velocity of sound, which is a function of several other pro- 

 perties which must correspond to it if the mathematical laws are 

 correct, or which must modify those laws in whatever respect they 

 are incorrect. 



1 determined the velocity of sound in solids by causing very fine 

 and long wires to vibrate longitudinally ; I diminished the diameters 

 until the sound remained invariable. My wires were only from 

 y^ths to Y^t^s °^ ^ millimetre in diameter, and 1-50 metre in length. 

 I placed them horizontally above a beam of oak, and fixed their ex- 

 tremities between two strong brass vices. 



The wires were very homogeneous, and the harmonics exactly 

 followed the laws of Bernoulli. The elevation of the sounds was 

 given by a sonometer, of which the brass cord was very fine and 

 very homogeneous. 



The following formulae give the velocity of sound as a function of 

 the other physical elements : — 



a^.= 9_ = yAl = 3^., (1) 



a, velocity of sound; g, force of gravity; E, coefficient of elas- 

 ticity ; A, mechanical equivalent of the heat, which I take as equal 

 to 420 kilogrammetres ; A, coefficient of linear dilatation ; p, che- 

 mical equivalent ; c = specific heat, and k=pc=iS to 42. 



Except for zinc, the difference between the values of A, calculated 

 and observed, are not very great, and must be attributed to causes of 

 which the influence can be appreciated ; in general the phaenomena 

 agree perfectly with the law. 



Velocity of sound in gases and saturated and non-saturated vapours, 

 for certain pressures and teniperattires. 



This portion of my researches was commenced some years ago 

 with apparatus which I have been constantly bringing to perfection, 

 and which I have rendered so simple and convenient that a chemist 

 or physicist may take the velocity of a sound as easily as the density 

 of a gas or vapour. The impossibility of employing sufficient time 

 continuously in my experiments had always suspended my labours, 

 until in M. Me'rit, Professor at the College RoUin, I found an assist- 

 ant of equal zeal and talent, with whom I have been able to resume 

 and bring them to a good conclusion. Of the two means which I 

 employ in taking the velocity of a sound in gases and vapours, I 

 shall describe the more simple. 



The apparatus consists of a glass balloon capable of containing 25 

 to 30 litres. Its neck, which is very short, is cemented into a brass 

 ferule which bears three tubes, two horizontal and opposite, and one 

 vertical or placed in the axis of the balloon. The latter bears at its 

 lower part an organ-pipe placed in the centre of the balloon, and its 

 exterior extremity receives a metal bellows, set in motion by a 

 copper rod fixed normally upon the moveable bottom. One of the ho- 



