But though congelation thus took place at five degrees below 

 the freezing point, it is proper that I mould ftate fome other 

 circumftances attending the experiment. 



The fea-water which I ufed came from the North Foreland, 

 which is at the mouth of the Thames, and confequently, not 

 being the fame with that of the ocean, was more eafily frozen. 



Beiides this, the quantity was fo fmall as not to cover a thin 

 china bafon deeper than an inch, both which particulars contribute 

 greatly to the more fpeedy formation of ice : it need fcarcely be 

 mentioned alfo, that the liquid to be frozen was in -a quiefcent 

 ftate. 



How much a coniiderable degree of motion impedes congela- 

 tion, may be inferred from what may be obferved in every river; 

 for as high as the tide hath any force, I doubt much whether any 

 ice is fcarcely ever formed in the fair open channel, during our 

 moft intenfe frofts. I attended to the Thames, in this refpecT:, 

 during the late feverity of the weather, and it feemed to me that 

 all the ice floated down from the upper parts of the river; but 

 packing afterwards between the lighters, occasioned the formation 

 of very large mafles. 



I have little doubt, from thefe circumftances, but that the open 

 fea, if it be frozen at all, muft require a much more intenfe cold 

 than twenty-feven ; allowing however any greater degree of cold 

 in the high latitudes, it feems deducible, from the experiments 

 of Dr. Higgins, that fea-water cannot be frozen into a folid 

 ftate, if compared with that of ice formed from the water of 

 livers ; nor will fuch -ice when melted become palatable, unlefs 

 -it hath been previoufly warned in frem water. 



Hence it feems to be almoft demonftration, that the floating 

 icq met with by navigators, being both folid and fweet to the 



R 2 tafte 



