20 



fluidity, and easy separation from other bodies. 3. Ex- 

 tremely solid. 4. Perfectly transparent. 5. Hard, rigid^ 

 duct indexible : as appears iroin the absolute impossibi- 

 lity of a impressing them. 



Salts melted in water, da not fill the vessel in propor- 

 tion to their bulk. It follows, that there are spaces be- 

 tween the particles of water to admit those of the salt. 

 Hence also we gather, that the \vatvy particles are ex- 

 tremely solid and inflexible, since, notwithstanding those 

 spaces, iio power can compress, or force them nearer 

 each other. 



8. When the particles of nitre that float in the air, 

 wedge the particles of water together, they become ice. 

 The -air lodged in the pores of the water is then greatly 

 expanded. Hence the water is lighter than before : but 

 at the same time it is less transparent : perhaps because 

 the passage of light is hindered by the interposal of these 

 nitrous particles. 



It is observable, 1. That all liquids, except oil, dilate 

 in freezing and grow lighter, ftay, even after they are 

 thawed, they are considerably lighter than before : 

 2. That water will not freeze in vatuo : 3. That water 

 which lias been boiled does not readily freeze : 4. That 

 water covered with oil of olives does not freeze readily ; 

 covered with nut oil, not at all : 5. That nut oil, oil of 

 turpentine and spirits of wine will not freeze at all : 

 6. That frozen water is covered with wrinkles, something 

 like rays drawn from a centre to the circumference. 



Though fluids are dilated near a *enth of their length, 

 petals are shortened by frost. If vessels made of me- 

 tals, however thick and strong, be filled with water, 

 c/ose stopped, and exposed t frost, the water will burst 

 f]ie vessels. A strong barrel of a gun, thus filled aud 

 stopped, will rend the whole length. 



Dr. Plot observes, that rivers are always found to 

 freeze first at their bottom. The same is observed by 

 watermen in the Thames, v/ho not only feel it at the bot- 

 tom with their pates, some thys before the surface is 



