36 



PHILOSOPHICAL TRANSACTIONS. 



[anno 1776. 



January 29, 



Therm, 

 theopen air. 



1770. 



19 



19 



19 

 19 

 IP 



19 



Effects, &c. 



A number of beautiful feathered crystah appsarcd in the jelly 

 glass ; they began to shoot from the lop, which was covered 

 with ice, toward the bottom ; when they reached it, the ther- 

 mometer rose immediately from 2i to -28.3. 



Ice began to form in the decanter though hardly perceptible at 

 the edge of the water. 



Crystals of a laminated appearance began to shoot downwards 

 obliquely from the ice at the surface, which at the edge of the 

 water was barely two-tenths of an inch thick ; no appearance 

 of ice in the middle of the surface. 



Crystals began to shoot round the neck of the decanter close to 

 the glass. 



The inside became covered with finely feathered crystals, which 

 made it impossible t» observe the height of the thermometer, 

 without raising it till the quicksilver in the tube appeared 

 above the ice. 



January 29, at 8 in the evening, Mr. N. exposed to the open air 2 similar 

 jars each 54 inches deep and \-^ inch in diameter ; one of which, for the sake of 

 distinction, he called a, the other b. a was filled with the seawater : b with 

 water taken out of a water tub, which was a mixture of rain and snow water. 

 In A 2 thermometers were placed ; one rested on the bottom ; the upper part of 

 the ball of the other was a quarter of an inch only below the surface 

 of the water ; one thermometer was also placed in b, resting on the bottom. 

 The following table shows the result. 



The surface of the water in b covered 

 with ice. 



Surface as before. 



No appearance of ice. 



The ice on the surface increased. 



Ice began to appear on the surface. 



Quite frozen. 



Crystals over every part of the glass. 



As before. 



During the time in which these observations were made, the thermometer in 

 the open air rose half a division. : 

 / The following table shows the result of some further observations on the 

 effects of cold on the seawater in the jar a of the last table, which had been 



