36 Saltncft of the Ocean. [Book Vf. 



mine there are houfes, chapels, and ftreets of rock 

 fait, which, when illuminated, afford a beautiful pro- 

 fpect. This fait js alfo obtained from fome fprings. 

 When found in the earth it is feldom cryftallized in 

 any regular form ; it has various degrees of whitenefs, 

 and is often found coloured ; in this latter ftate it is 

 more particularly called fal gem, becaufe it often has 

 the appearance and tranfparency of gems. . 



The ocean differ.? in faltnefs in different climates. 

 It is falter towards the equator than rear the poles. 

 This feems to arife from the different quantities of 

 water which are evaporated, in proportion to thofe 

 which fall in rain. One pound of fea water in the 

 Baltic yields about a quarter of an ounce of fait ; near 

 Holland half an ounce ; and in the Britifh feas about 

 two ounces. Boyle has alfo obferved, that in places 

 of great depth the water is falteft at the bottom. 



In the voyage made towards the north pole in 1775, 

 it was found, that the fea-water at the Nore contained, 

 not quite one thirty-fixth of fait j at the back of Yar- 

 mouth fands, not quite one thirty fecond ; off Flam- 

 borough Head, rather more than one twenty-ninth ; 

 off" Scotland, rather lefs than one twenty-ninth j 

 ..latitude 74, at fea, one twenty-ninth; latitude 78, 

 rather lefs than, one twenty-eighth ; latitude 80, near 

 the ice, not quite one thirtieth ; latitude 8of-, under 

 the ice, not quite one twenty-eighth ; latitude 68, 

 46, rather more than one -twenty- eighth * latitude 65, 

 at fea, rather lefs than one twenty- eighth. Dr. Hales 

 got only one twenty- feventh from water taken up in the 

 Mediterranean, and cne twenty-ninth from water taken 

 up at the Nore. Dr. Rutty fays, he procurred one 

 twenty- fifth from water taken up in latitude 65; one 

 twenty-eighth from water taken up near Dublin \ and 

 one thirtieth from water taken up at Dungarvan ; and 

 Dr. Lucas, that he obtained one twenty-fifth from water 



taken 



