that there is more Salt in the former: tho' this be but a weak Reason. 4. A fourth Caufe is the frequency and scarcity of Rain or Snow. In the northern Countries they have both very frequent: but under the Torrid Zone they have no Rains at all for fome Parts of the Year, and at other Times they are almost conftant. Therefore, in thefe Places, the Ocean, near the Shores, is not fo falt in rainy Months as it is in dry ones. Yea in feveral Places on the Coaft of Malabar, in India, the Sea-Water taftes fweet in the rainy Months, by reafon of the vast quantity of Water which flows from off Mount Gate, and falls there into the Sea. This is the Reason why, at different Times of the Year, the fame Parts of the Ocean are of different Degrees of Saltnefs. But because in the northern Countries there are constant Rains and Snow almost throughout the whole Year, therefore the Sea there is lefs falt than in the Torrid Zone. 5. A fifth Caufe is the different quality of the Water to diffolve and mix the Salt with it; for hot Water diffolves Salt much fooner than cold: and therefore tho' there were the fame quantity of Salt under Water in the Chanels of the Sea, near the Poles, as about the Equator; yet because the Water is cold there, it cannot fo quickly diffolve it into minute Particles and mix with it, as the Water in the Torrid Zone which is hotter. 6. A fixth Caufe is the great and many large Rivers that empty themselves into the Sea; but thefe only cause an Alteration upon the Coasts; for the main Ocean is not fenfibly affected by them. Mariners relate that upon the Coaft of Brafil where the Rio de la Plata empties itfelf into the Sea, the Ocean lofes it's falt Tafte, at almoft fifteent Leagues Distance from the Shore; and the fame P 4 may may be faid of the African Ocean on the Coast of Congo, and in feveral other Places, as about Malabar in India, (as was obferved before) &c. To these Causes we may add the fpringing up of fresh Water in fome places from the Bottom of the Sea. THESE Caufes (whether feparate or united) make a great variety of Saltnefs in different Parts of the Ocean, and by these that variety is explained and accounted for. HENCE there is given a Reason why the Water of the German and northern Ocean will not yield fo much Salt by boiling, as the Water of the western Ocean about Spain, the Canary Islands, and Cape Verd in Africa, (from whence the Dutch fetch abundance of Salt and tranfport it to several northern Countries, viz. to Prufia, Poland, &c.) because these Coafts are nearer the Torrid Zone than the other; tho' perhaps both their Chanels may contain an equal quantity of Salt. THE Sea-Water in the Ethiopic Ocean, over against Guinea, yields white Salt, with once boiling, as fine as Sugar, such as neither the Spanish Ocean, nor any other in Europe will produce at once boiling. PROPOSITION XI. Why Rain-Water catched in the middle of the Ocean is found to be fweet and fresh, when it proceeds from the Vapours which are exhaled from the Sea; whereas the Water, which, by boiling or distilling, we feparate from the falt Water of the Sea, is found to be falt. THOSE that have diligently fearched into the Secrets of Nature, I mean the learned Chymifts, (not those ignorant Pretenders to Chymistry) have 217 have hitherto laboured in vain to find out a Method of diftilling or extracting fresh Water from the Sea-Water, which would be of great use and advantage to Navigation (g). And tho' both by Decoction and Diftillation, which are in Effect the fame, there is Salt left in the Bottom of the (g) Mr Hauton first found out the Secret of making SeaWater fweet. It confilts firft in a Precipitation made with the Oil of Tartar, which he knows to draw with fmall Charges. Next he diftils the Sea-Water; in which the Furnace taketh up but little Room, and is fo made, that, with a very little Wood or Coal, he can diftil twenty four French Pots of Water in a Day; for the cooling of which he hath this new Invention, that instead of making the Worm pafs thro' a Veffel full of Water (as is the ordinary Practice), he maketh it go thro' a Hole, made on purpose out of the Ship, and to enter in again thro' another; fo that the Water of the Sea performeth the cooling Part; by which means he faveth the Room which the common Refrigerium would take up; as alfo the Labour of changing the Water when the Worm hath heated it. But then, thirdly, he joins to the two precedent Operations Filtration, whereby perfectly to correct the malignity of the Water. This Filtration is made by means of a peculiar Earth, which he mixeth and stirs with the diftilled Water, and at length fuffers to fettle at the Bottom He maintains that this diftil. led Sea-Water is altogether fa I lubrious: he proves it from Experience, it having been given to Men and Beafts, without any ill Effect at all upon them. Secondly, from Reason grounded on this, that that peculiar Earth being mixed with the distilled Water, blunts the Points of the volatile Spirits of the Salt, and ferveth them for Sheaths, if I may fo fpeak, taking away their Force and malign fharpnefs. Philof. Tranf. abridged by Lowthorp. Vol. 2. Page 297. I have been credibly informed by experienced Sailors (particularly fome that had an Engine on Board) that Salt-Water made fresh by Distillation, would not quench Thirst; but that, when they had drank as much as they could get down, their Thirst, was not at all abated. So neceffary are the Impregnations, which the Waters receive in their pa fages about the Earth, to make them nutritive. And the richer, and more fulphureous, those Impregnations are, fo much the richer, and better, fuch Waters are accounted. An instance of which we have in the Richness and Spirituousness of the Thames-Water at Sea, which no doubt it receives from it's Impregnations by the Soil, and Filth, of the London Kennels, Veffel, Veffel, yet the Water thus separated is still salt, and not fit for drinking, which feems ftrange to those that are ignorant of the Cause of it. This is taught by Chymistry (which is the trueft Phliofophy), by the help of which there are found two kinds of Salt in all Bodies, which tho' they perfectly agree in Tafte, yet they exceedingly differ in other Qualities: Artifts call the one fixed Salt, the other volatile. The fixed Salt, because of it's Gravity, is not evaporated by Distillation, but remains in the Bottom of the Veffel: but the volatile Salt is fpirituous, and indeed nothing but a moft fubtile Spirit, which is easily raised with a very gentle Fire; and therefore in Diftillation af cends with the fweet Water, and is well mixed with it by Reafon of the fubtilty of it's Particles. This fixed and volatile Salt is found, by Chymifts, to be not only in Sea-Water, but almost in all Bodies, tho' more in fome than in others; in Herbs that tafte fharp there is more, but in oily and infipid Things lefs. The Difficulty therefore lies in feparating the volatile Salt, or the falt Spirit from the Water; for it is this which hath rendered all the Efforts hitherto fruitless. BUT why Rain-Water fhould be as fweet and fresh on the main Ocean as it is at Land, when it is generated from Exhalations, which arife from the Sea by the Heat of the Sun, or is exhaled by the Force of fubterraneous Fire, which Evaporation no way differs from Distillation, there feemeth to be a fourfold Caufe. 1. A flow and gentle Evaporation, by which only the more fubtile Part is exhaled out of the Ocean, which tho' it contain the volatile Spirit of Salt, yet it is in a lefs quantity than when the Evaporation is made by a strong Heat. 2. The long Space which this Vapour paffes thro' before it arrives at that Region of the Air where it is con denfed denfed into Rain: in which Paffage it is poffible that the faline Spirit may be by degrees feparated from the watery Particles. 3. The Mixture of other fresh Particles of Water that are in the Air. 4. The Refrigeration and Coagulation or Condenfation of the Vapour. For these Vapours in their afcent from the Ocean become, by degrees, colder, and mixing with others in their Way, they are condensed and turned in Clouds; and in this Refrigeration and Condensation the faline Spirits fly away, with fiery Particles, into a higher Place of the Air. BUT why this doth not happen in Distillation (where the Vapours exhaled become more cool and condensed) proceeds from hence: 1. In this fhort Paffage the faline Spirit fticketh clofe to the watery Particles. 2. The Vapour is kept in a Veffel which doth not admit the Spirit to fly thro' it. PROPOSITION XII. Sea-Water is heavier than fresh; and Sea-Water in one Place is heavier than in another (b). THE Reason of this is plain from what we have faid before, viz. that the Sea-Water contains a fixed Salt which is a much heavier Body than |