22 Dr. BtAGDEN’s Report 
more predominant ingredient. V\ere it not for a certain 
efftdc attending the mixture of water and 1 pints which has 
been called their mutual penetration, the fpecihc gravuy of 
thefe compofitions, in a given degree of heat would be Amply 
in the arithmetical proportion of the quantity of each of the 
fluids entering into them. But whenever different fubftances, 
which have a ftrong tendency to unite together, are mixed, tne 
refulting compound is found to occupy lefs ipace than the mo- 
ftances forming it held in their i'eparate fldte, wherefore t e 
fpecife gravity of fuch compounds is always greater than would 
be riven by a fimple caculation from the volume of their in- 
gredients. Though it be a general faff, that Inch a decreaie o 
bulk takes place on the mixture of fubftances which have a 
chemical attra&ion for each other, yet the quantity of t ns 
diminution is different in them all, and, under our prefent 
ignorance of the intimate compofition of bodies, can be deter- 
mined by experiment only. To afeertain, therefore the quan- 
tity and law of the condensation refulting from this mutual 
penetration of water and fpirit, was the firft object to which 
the- following experiments were directed. _ 
All bodies, in general, expand by heat ; but the quantity o 
this expanfion, as well as the law of its progrefiion, are pro- 
bably not the fame in any two fubftances. In water and lpmt 
they are remarkably different. The whole expan lion of pure 
fpirit from 30° to ioo° of Fahrenheit’s thermometer, is 
not lefs than -J T th of its whole bulk at 3 °° 5 whereas tha *.° 
water, in the fame interval, is only ^- 5 th of its bulk. 1 be 
laws of their expanfion are ftill more different than the quanti- 
ties. If the expanfion of quickfilver be, as ufual, taken for 
the ftandard (our thermometers being conftruaed with tha 
fluid), the expanfion of fpirit is, indeed, progreflively mcr « - 
