Pbjjlology — Gravity of Water. '427 



fays, he has feen this air, thus compreffed, produce a very 

 great degree of cold when the cocks were opened to fuffer 

 it to efcape. To demonftrate this in an eafy manner, let a 

 fmall quantity of water be put into a compreffing machine. 

 When the air efcapes, it iffues with a hiding noife, and 

 carries with it a part of the water; and at the end of the 

 operation, the water adhering to the cock, will be found 

 converted into ice. To explain this phenomenon, we may 

 fuppofe that a portion of the water, which is carried off by 

 the air, is reduced to an aeriform ftate, or that of vapour. 

 But this could not be the cafe, unlefs a pretty confiderablc 

 quantity of caloric were combined with the vapour. The 

 remaining drops of water are therefore fufficiently deprived 

 of it to be congealed. It is in the fame manner that the 

 rapid evaporation of ether, applied to the ball of a thermo- 

 meter, makes the liquor fpeedily defcend feveral degrees. 



PHYSIOLOGY. 



Dr. Soemmering has proved, by a great number of obfer- 

 vations, that the degree of intelligence of different animal* 

 is always in proportion to the bulk of the brain, compared 

 with that of the nerves. Man has the moft voluminous 

 brain, and his nerves are very fmall : it is this which gives 

 him his high degree of intelligence. The afs has very large 

 nerves, and a very fmall brain. Dr. Ebel has publifhed on 

 this fubject a very interefting differtation, which we hope 

 foon to be able to lay before our readers. 



GRAVITY OF WATER. 



Bodies are dilated by warmth, and confequently become 

 fpecifically lighter the hotter they are. On the contrary, 

 they are contracted by cold, and become fo much denfer the 

 colder they are. But this law of condenfation is fubject to 

 fomc exceptions : melted metal, for example, dilates to a 

 certain degree as it becomes folid 3 water experiences the 



fame 



