i *54 ] 
proceeded very flowly, juft as the water that lies 
about the fait appears thick and loaded, and while 
it continues at reft, the fait is diftblved very flowly. 
He alfo obferves on the fame occaiion that evapo- 
ration is vaftly promoted by a current of frelh air 
pafling over the exhaling furface j and this I have 
no doubt happens for the fame reafon that folution is 
greatly promoted by agitation, which continually 
brings frefti particles of the fluid into contact with 
the body, it diflblves, in the place of thofe that have 
been already faturated. 
Secondly ; into a glafs of clear cold water throw 
a lump of any kind of fait which is foluble in it,, 
and when it has ftood a little time, fhake the glafs,.. 
or ftir the water gently with a wire, and the water 
which is faturated with the fait will rife up among 
the reft, of the water in curled wreaths, or long ftriae, 
which will render the water fomewhat opake, 
caufing it to refrad; in different directions the light 
of an object feen through it, and it will make the 
object appear to have a tremulous motion, and this 
will continue until all , parts of the. water are equally 
impregnated with the fait, and then its tranfparency 
will be reftored. As the parts of the water, which, 
are impregnated with the fait, are of different den- 
ftties from the reft, while they are mixing together 
they muft occafion thofe refraCtions, and this appa- 
rent tremulous motion, which will ceafe as foon as all 
the water becomes of the fame denfity. The very 
fame appearances will attend the mixing together of 
any two fluids of different denflties,, and.wich will, 
thoroughly incorporate with each other. 
In 
