Page:Philosophical Transactions - Volume 001.djvu/54

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with water, and exposed to the cold Air, do burst; and where also the weight is expressed, that will be removed by the expansive force of Freezing? Whereunto an Inquiry is subjoined, whence the prodigious force, observed in water, expanded by Glaciation, should proceed? And whether this Phænomenon may be solved, either by the Cartesian, or Epicurean Hypothesis?

11. What is the Sphere of Activity of Cold, or the Space, to whose extremities every way the Action of a cold Body is able to reach: where the difficulty of determining these limits, together with the causes thereof; being with much circumspection mentioned, it is observed, that the Sphere of Activity of Cold is exceeding narrow, not onely in comparison of that of Heat in Fire, but in comparison of, as it were, the Atmosphere of many odorous Bodies; and even in comparison of the Sphere of Activity of the more vigorous Loadstones, insomuch, that the Author hath doubted, whether the Sense could discern a Cold Body, otherwise then by immediate Contract. Where several Experiments are delivered for the examining of this matter, together with a curious relation of the way used in Persia, though a very hot Climate, to furnish their Conservatories with solid pieces of Ice of a considerable thickness: To which is added an Observation, how far in Earth and Water the Frost will pierce downwards, and upon what accounts the deepness of the Frost may vary. After which, the care is inculcated, that must be had, in examining, whether Cold may be diffused through all Mediums indefinitely, not to make the Trials with Mediums of two great thickness: where it is made to appear, that Cold is able to operate through Metalline Vessels, which is confirmed by a very pretty Experiment of making Icy Cups to drink in; whereof the way is accurately set down. Then are related the Trials, whether, or how, Cold will be diffused through a Medium, that some would think a Vacuum, and which to others would seem much less disposed to assist the diffusion of Cold, than Common Air it self. After which follows a curious Experiment, shewing whether a Cold Body can operate through