


389. Mr. Wepewoon's Method of conneting — 
the fame inftant, in the fame veflel, and-even in the ech 
fragment of ice, isa faét of which I have the fulleft” evidence 
that my fenfes can give me; and [ fhall take the liberty of fug- 
gelting a few hints, which may tend perhaps to elucidate their — 
caufe, and to fhew that they are not fo incompatible as at firft 
fight they appear to be. a 
It oceurred to me at firft, that water highly attenuated and 
divided, as when reduced into vapour, may freeze with a lefe ~ 
degree of cold than water in ‘its aggregate or grofler form 3. 
hence hoar-froft 1s obferved upon grafs, trees, &c. at times 
when there is no appearance of ice upon water, and when the 
thermometer is above the freezing point*. BorRHAAvE, I 
find, in his elaborate theory of fire, affons 33° as the freezing 
point of vapour, and even of water when divided only by being 
imbibed in a linen cloth. ) 
* Tam aware, that experiments and obfervations of this kind are not fully’ 
cecifive; that the atmofphere may, in certain circumftances, bemuch warimer or 
colder than the earth and waters, which, invirtue of their denfity, are far more 
retentive of the temperature they have once reccived, and lefs fufceptible of 
tranfient imprefions ; that even infentible undulations of water, from the flighteft 
motion of the air, by bringing up warmer furfaces from below, may prove a further 
impediment to the freezing; and, therefore, that the degree of cold, which is 
fufficient to produce hoar-froft, may poffibly, if continued long enough, be fufi- 
cient alfo te produce ice Iam not acquainted with any fatisfactory experiments. 
or obfervations yet made upon the fubjeSt; nor do I advance the principle as a 
certain, but as a probable one, which occurred to me at the moment, which is 
countenanced by general obiervation, and confentaneous to many Known fadts ; 
for there are numerous initances of bodies, in an extreme flate of divifion,’ 
yielding ealily to chemical agents which, before fuch divifion, they entirely refift s 
thus fome precipitates, in the very fubtile ftate in which they are at firft extricated 
from their diffolvents, are re-diffolved by other menftrua, which, after their 
concretion into fenfible molecule, have no action upon them at all, 
7 Now, 
