280 Dr . Blag den’s Experiments on 
fhot rather more readily than fome other folutions; which I 
aferibed, from the analogy of ray former experiments, to its 
lefs tranfparency. Though the common ialt did not form a 
turbid folution, yet there was fomething of a greyifh caft, 
much like what is produced by the mixture of a fmall portion 
of clay with pure water ; and the caution in conducing the 
operation, neceflary to make folutions of this fait cool a cer- 
tain number of degrees below their freezing point, feemed to 
be nearly the fame as would be required with water equally 
tinged by means of clay. 
2. When the folution was very ftrong, nearly faturated with 
the fait, cooling it tended fomewnat to leflen this greyifh caft, 
to render it rather more limpid : as was particularly the cafe in 
a faturated folution which I cooled to o°. I fufpedt this effect 
takes place when the folution begins to expand with the cold. 
3. In the ftrong folutions, when the proportion of fait was 
as much as one- fifth, before the real congelation came on 
which reduced the whole to one temperature, feveral fmall 
ftellated cryftals formed in the liquor, which increafed very 
flowly. Thefe were real ice of the fait water; but the cold 
being in this cafe very little below the freezing point of the 
folution, there was little power to make them fpread ; and 
fometimes, when this occurred, I believe, part of the folu- 
tion toward the top was rather above than below the freezing 
point. Similar phenomena were obferved, and in a ftill more 
remarkable manner, in the folutions of fome other falts, al- 
ways when they were very ftrong : and it may be given as a 
general fa£t, that in folutions approaching to faturation, though 
the formation of one glacial cryftal does, as in pure water, tend 
to make the whole freeze and come up to an uniform tempera- 
ture, yet the fhooting goes on much more flowly, as if the 
2 fait 
