l60 PHILOSOPHICAL TKANS ACTIONS. [ANNO 1781. 



and put a little water in it, so as to fill about half an inch length of it, as is 

 shown at cb in the figure. Into this tube a slender wire h is also introduced, 

 the lower extremity of which is twisted in a spiral manner, and serves to draw 

 up the ice, when formed. Things being thus prepared, I hold the glass tube by 

 its upper part a with the fingers of the left hand, and keep it continually and 

 gently turning round its axis, first one way, and then the contrary; while with 

 the right hand I hold the phial containing the tether in such a manner as to direct 

 the stream of aether on the outside of the tube, and a little above the surface of 

 the water in it. The capillary aperture d should be kept almost in contact with 

 the surface of the tube that contains the water. Continuing this operation for 2 

 or 3 minutes, the water will be frozen as it were in an instant ; since it will ap- 

 pear to become opaque at the bottom b, and the opacity will ascend to c in less 

 than half a second of time, which exhibits a beautiful appearance. This con- 

 gelation, however, is only superficial, and in order to congeal the whole quan- 

 tity of water, the operation must be continued a minute or 2 longer; after 

 which the wire h will be found to be kept very tight by the ice. Now the 

 bottle with the aether is left on a table or other place, and to the outside of the 

 glass tube the hand must be applied for a moment, to soften the surface of the 

 ice, which adheres very firmly to the glass, and then pulling the wire h out of 

 the tube, a solid and hard piece of ice will come out, fastened to its spiral 

 extremity. 



Instead of the wire h sometimes I put a small thermometer into this tube, so 

 as to have its bulb immersed in the water. With this thermometer I have ob- 

 served a very remarkable phenomenon, which seems to be not explicable in the 

 present state of knowledge concerning heat and cold. This is, that water will 

 freeze in the winter with a less degree of cold than it will in the summer, or 

 when the weather is hotter : for instance, in the winter the water in the tube ab 

 will freeze when the thermometer is about 30° ; but in the summer, or even 

 when the temperature of the atmosphere is about 6o°, the quicksilver in the 

 thermometer must be brought 10 or 15, or even more, degrees below the freez- 

 ing point, before the water which surrounds the said thermometer will be con- 

 verted into ice, even superficially ; hence it appears, that in the summer time a 

 greater quantity of aether and longer time are required to freeze a given quantity 

 of water, than in the winter ; not only because then a greater degree of heat is 

 to be overcome, but principally because in the summer a much greater degree of 

 cold must be actually produced before the water that is kept in it will assume a 

 solid form. When the temperature of the atmosphere has been about 40°, I 

 have frozen a quantity of water with an equal weight of good tether, but at pre- 

 sent, being summer, between 2 and 3 times the quantity of the same tether must 

 be used to produce the same effect. 



