156 ANNUAL OF SCIENTIFIC DISCOVERY. 



in churches ; the greater cost, but this is more than counterbalanced by 

 its superior excellence ; the greater space required ; and the fact, that 

 the organist must be a thorough master of the science of music. The 

 instrument spoken of is placed in the chapel in Indiana Place, Boston. 



ON CERTAIN PHENOMENA OF THE FORCED DILATATION OF LIQUIDS. 



LET a strong capillary tube, closed at one end and drawn out at the 

 other to a slender point, be filled with water at the temperature of 82 J 

 or 86 F. ; if this tube is cooled down to 64, so as to cause a certain 

 quantity of air to enter it at the open point, and it is then closed, and 

 again heated to 86, and gradually higher, after a certain time the air 

 is completely dissolved. If cooled to 64, the original temperature at 

 which the tube contained at the same time air and liquid, it is seen 

 that the water continues to occupy the whole of the internal capacity, 

 and maintains thus an invariable density between 82 and 64. Its 

 temperature may even be lowered still more. At this moment the 

 least shock or collision, the least vibration, causes the instant re- 

 appearance, with a sort of ebullition, a slight noise, and a shock more 

 or less perceptible, of the gas dissolved in the water. It dilates rapid- 

 ly, and in less than a second has resumed its primitive volume at 64. 

 The same phenomenon occurs with very many other gases and liquids, 

 as well as with air and water. With mercury it does not occur. In 

 these phenomena there are two things very distinct ; 1 . An unstable 

 supersaturation of the liquid by the gas produced under the influence 

 of the pressure. 2. A state of forced dilatation of the liquid ; the 

 latter an instant before the vibration fills the volume which the gas 

 occupies an instant after conjointly with it, and this volume is the 

 same which the dilated liquid filled on an elevation of temperature. 

 The variation of density thus produced is enormous ; for water it is 

 equal to ? 5 of its volume at 04. for alcohol to s . for ether to ^- 

 Such an effect could be produced otherwise only by a pressure of 50 

 atmospheres for water, and of 150 for ether. This phenomenon prob- 

 ably accompanies all supersaturations, but at variable degrees and in 

 various directions, without being capable of being proved. The forced 

 dilation of water and ether is also independent of supersaturation, it 

 having been produced in vacua. Bcrthelot, Comptcs Rendus, June 24. 

 Brewster's Philosophical Magazine, Aug. 



EFFECT OF PRESSURE IN LOWERING THE FREEZING POINT OF 



WATER. 



IN 1849, Mr. James Thompson, of Glasgow, read a paper before the 

 Royal Society of London, in which it was demonstrated, that if the 

 fundamental axiom of Carnot's theory of the motive power of heat be 

 admitted, it follows, as a rigorous consequence, that the temperature 

 at which ice melts will be lowered by the application of pressure. In 

 this remarkable speculation, an entirely novel physical phenomenon 

 was predicted in anticipation of any direct experiments upon the sub- 

 ject ; and the actual observation of the phenomenon was pointed out 

 as a highly interesting object of experimental research. 



