390 
Sc ientijic Intelligence . 
cited by a degree of heat superior to the first, and is irrecover- 
ably destroyed by a higher temperature. — *3. All bodies capable 
of coagulating albumen, take away from phosphorising matter 
its power of phosphorescence.— -4. The phosphorescence cannot 
take place but in a gas which contains oxygen. — 5. It is ex- 
cited by the galvanic pile, but no effect is produced upon it by 
electricity. — 6. The phosphorescent matter is composed princi- 
pally of albumen. 
ACOUSTICS. 
5. Velocity of Sound.— M. Richard Van Rees, in an inau- 
gural dissertation on Sound, has shewn theoretically, that the ve- 
locity of sound in common air is 341.54 metres in a second. 
In obtaining this result, he adopts the theory of Laplace, and 
founds his calculations on the data given by MM. Delaroche 
and Rerard on specific heat. The experiments on the velocity 
of sound, made at Dusseldorf by M. Benzenberg, give for the 
velocity of sound 333.7 metres, about 2J feet more than the ve- 
locity obtained from the experiments made at Paris. 
6. Propagation of Sound in Elastic Fluids. — M. Van Rees, 
in the last chapter of the same work, has given the results of 
his experiments on the propagation of sound on elastic fluids, 
made with great care, and under the auspices of MM. Fram- 
eyer and Moll. The following are some of the results : 
Velocity 10° of Centig. therm. 
Hydrogen, . . , 1233.3 Metres. 
Ammonia, ..... 432 
Vapour of water, temp. 54° cent. 422.6 
Carbonic oxide, .... 341.1 
Azote, ...... 339.0 
Carburetted hydrogen, . . . 377.4 
Oxygen, • 317.7 
Deutoxide of azote, . • • 317.4 
Sulphuretted hydrogen, . . . 305.7 
Hydrochloric acid, .... 298.8 
Carbonic acid, . • ♦ • 270.7 
Protoxide of azote, . • . 270.6 
Vapour of alcohol, . • • 262.7 
Sulphurous acid, .... 229.2 
A fuller account of these experiments will be found in the 
Journal de Physique , Jan. 1821, tom. xcii. p. 42. 
