See that article, Encycl. and Chemistry-Index in this Supplement. We have introduced the word here, to notice some experiments made by Professor Jacquin of Vienna, at the desire of Dr Chladni, on the different gases as the vehicle of sounds. A glass bell was furnished with a metallic stopper cemented to a neck at the top; and in the bore of this cock, within the glass, a small flute or pewter (certain) about six inches in length was fixed. The glass being then placed on the shelf of the pneumatic vessel, and filled with any particular kind of gas, a bladder also filled with the same gas, and provided with a cock, was adapted to the external aperture of the cock belonging to the bell-glass. In this disposition of the apparatus, the flute was made to sound by gently pressing the bladder. Comparative experiments were made with atmospheric air, oxygen, hydrogen, carbonic acid, and nitrous gas. The intensity of the sound did not vary; but when compared with that produced by atmospheric air, the oxygen gas gave a sound half a tone lower; azotic gas, prepared by different methods, constantly gave a sound half a tone lower; hydrogen gas gave nine or eleven tones higher; carbonic acid gas gave one-third lower, and nitrous gas also very nearly a third lower. A mixture of oxygen gas and azote, in the proportions of the atmospheric air, afforded the tone of this last; that is to say, it was half a tone higher than each of the component parts alone. When the two gases were not uniformly mixed, the sound was abominably harsh. Chladni intends to give a fuller account of these interesting experiments. Journal de Physique, Vol. IV. N. S. p. 57.