5 ft On (he Exp msion and Contraction of Water, 



ill a fiuHl state. Put owing to the reciprocal affinity of' 

 these iiioleciilae this attraction is very IVeble, and on sud- 

 denly shaking the water they rush together, I'orniing S 

 crystalline mass, setting tree the caloric they held around 

 them, causing by that liberation a rise in the thermo- 

 meter. In the same manner we can luring so near as to 

 touch, globules of mercury, which have been previously 

 moistened with water, without their runnino: into one ho- 

 mogeneous mass.; but giving the vessel in which they are 

 plnced a sudden shake, they become united, parting with 

 the water each had attracted around it. This experiment 

 is easily shown by throwing quicksilver upon any flat sur- 

 face that has hati si)me water poured upon it ; then jrently 

 pushing the glolndts of mercury, so- as just to touch each 

 other, they will not unite, owing to the pellicle of water 

 which surrounds each. Upon the vessel being agitated, an 

 union instantly lakes place. 



The next remarkable occurrence is the great and suddea 

 expansion that takes place upon the water l)eing converted 

 into ice. I would now suppose that these atoms have 

 reached their maximum of expansion, or that they deviate 

 in the greatest possible degree from their spherical shape, 

 and assume probably that of the primitive crystal. For 

 after having obtained the primitive crystal of any body, we 

 have, if we continue the chipping and diminish it ever so 

 much, always the same figure. Atrain, if we apply heat,, 

 from the 3-2° there is observed a conTraclion, until the ther- 

 mon;eter rises to the 39^ or 40', owing to these integrant 

 molecules of the crystals again assuming the spherical 

 form: after this the water begins to expand, which I 

 should imagine is owing to the caloric gradually forcing 

 these spheres further apart, and, if continued, separates them 

 beyond the limit of the attraction tliey exert amongst them- 

 selves. These atoms, being lighter than air, fly ofl' in a 

 slate of vapour; and as they are now out of the sphere of 

 each other's attraction, they are enabled to attract more 

 forcibly around them the particles of caloric ; and hence 

 the increase of capacity for caloric whicli is observed to 

 take place when water is converted into vapour. 



In tiie above paper, the words contact and touch have 

 been frequently employed; these terms arc not to be un- 

 derstood in an abstract sense, but merely to denote that the 

 particles of matter approach each other extremely near; — as 

 111 the experiment on the globules of mercury it is said they 

 are placed so near as to touch. That this is not the case is 



evident. 



