The history of the Royal-Society of London for the improving of natural knowledge by Tho. Sprat.
Sprat, Thomas, 1635-1713., Cowley, Abraham, 1618-1667. To the Royal Society.
Page  230


A Small Stone of the kind, called by some Authors Oculus Mundi, being dry and cloudy, weighed
5 gr. 200/256
The same being put under Water, for a night and somewhat more, became transparent, and, the superficies being wiped dry, weighed
6 gr. /256
The difference between these two weights
0. 50/256
The same Stone kept out of Water one day and be∣coming cloudy again, weighed
5. 225/256
which was more than the first weight
0. 16/256
The same being kept dry two dayes longer, weighed
5. 202/256
which was less than at first
0. 7/256
Being kept dry something longer, it did not grow sen∣sibly lighter.
Being put under Water for a night, and becoming again transparent, and wiped dry, the weight was
6. 3/256
the same with the first, after putting in Water, and more than the last weight, after keeping of it dry
0. 57/256
Another Stone of the same kind, being variegated with milky, white and grey, like some sort of Agates, while it lay under Water, was always invironed with little bub∣bles, such as appear in water before boyling, next the sides of the vessel.
Page  231There were also some of the like bubbles on the surface of the water just over it; as if either some Exhalations come out of it, or that it did excite some fermentation in the parts of the water contiguous to it.
There was little sensible difference of Transparency in this Stone, before the putting under Water, and after: To be sure the milky white parts continued as before, but more different in weight, than in the former. For whereas, before the putting into the water, the weight was-18 gr. ••/118 after it had lyen in about twenty four hours the weight was 20 gr. 27/123; so the difference was
1 gr 5/18
The same Stone was infused in the water scalding hot, and so continued for a while after it was cold, but got no more weight, than upon infusing in the cold; neither was there any sensible difference in the weight both times.