Some Experiments about Freezing, and the Difference Betwixt Common Fresh Water Ice, and That of Sea Water: Also a Probable Conjecture about the Original of the Nitre of Aegypt: By Dr. Lister, Fellow of the Royal Society

Some Experiments about Freezing, and the difference betwixt common fresh Water Ice, and that of Sea Water: also a probable Conjecture about the Original of the Nitre of Egypt: by Dr. Lister, Fellow of the Royal Society. December 3d 1684 at Night I exposed 4 Glasse bottles in the open aire upon the ground to freeze; viz, of the Red-Natron Water from Egypt; of a strong Solution of Nitrum Murarium in fair Water, of Sea Water taken up at Scarborough and more then halfe Evaporated; of the Sulphur well at Knaresborough, that is, of natural brine evaporated to the same height with the Sea Water. Note, that the 4th in the morning, the Solution of Nitrum Murarium was halfe of it Ice, but not any of the rest. The 6th in the morning, the bottle of Nitrum Murarium was most Ice; the Sulphur Water had no Ice that I could perceive at all in it: the Natron had much Ice at the bottom of the bottle; and the Scarborough Sea Water was not without flakes of Ice. The Icicles of the Natron were prettily figured, as is represented in Fig. 1. the Icicles of the Sea Water were also figured in oblong squares, as in Fig. 2. and were brittle and transparent. I let the drained Icicles of Natron before the fire, which did readily enough melt & dissolve into water again; this Ice was both alike salt in Ice and in Water, much like its Water to the tast, out of which it was frozen. In like manner having drained the Sea Water Ice, and exposed it before the fire; these Icicles became soft and moist by degrees, but at length rather Evaporated, than quite melted away; and having taken up a good thick lump lump of common Ice, at least a 100 times their thickness & bulk, this in a few moments at the same distance before the fire, grew wetter and wetter and dissolved into water, whereas the Salt Icicles after 3 quarters of an hour, lying before the fire did at length dry into a white powder perfect Salt, the moisture totally Evaporating. Also the Sea Water Icicles tasted very Salt, when first taken out of the Water. I repeated the same experiment of exposing to freeze the bottles of Natural Brine of Knaresborough Sulphur well halfe Evaporated, and Scarborough Sea Water, the same as formerly, the 7 and 8th instant at Night, & with the like success; viz, no Icicles in the natural brine, but the same large ones as above described I had in the Sea Water, but not till after the 2d Nights keen freezing. These Salt Icicles continued unthawed in the bottles, though they were brought into the House and kept in a warm room long after all other Ice within doors was gone, viz, till the 12th instant at Night, when the Icicles also were dissolved and vanished. From which Experiments we note, 1. that there may be Salt Ice from Sea Water frozen, which the Experiments of this S. of the last year did not seem to favour. 2. that there is a real difference betwixt natural Brine, and Sea Water; as there is betwixt the Salts themselves, which they yield. 3. That the great floating Mountains of Ice in the Northern Seas (if upon strict Tryal they shall be found to be salt, which should be further enquired into,) are not only the effects of many yeares freezing, but also much of their magnitude may be owing to the natural duration of that sort of Ice. Before I end, give me leave to guess at the original of the Nitre of Egypt, which the Experiments made about it at Oxford plainly shew to be little different from Sal Armoniac. That considering that it raines little or nothing comparatively to the great heats, in Egypt; and that the Lakes there are only once a year furnish'd with fresh Water from the overflowings of Nile; also that vast tracts of Land there and all over Asia are naturally covered with fossil Salt; again those Lakes are furnish'd with vast Animals as Crocodiles, Hippopotami, and without doubt great variety of other lesser Vermin; these things I say, well considered, it is easy to think, that in a years time, most the Salt Water of those Lakes has past through the Bodies of those Animals, and consequently is become Urinous or Salin-Urinous, as is the nature and composition of factitious Sal Armoniac.