10 PHILOSOPHICAL TRANSACTIONS. [aNNO 1 683-4. 



By means of this problem, any sound may be conveyed to a very great distance 

 and heard. 



3. The third problem is, that a sound may be conveyed from one extreme to 

 the other, or from one distant place to another, so as not to be heard in the 

 middle. By the help of this problem, a man may talk to his friend at a very 

 considerable distance, so that those in the middle space shall hear nothing of 

 what passes between them. 



Certain Observations on the Midland Salt Springs of JVorcestershire, Stafford- 

 shire and Cheshire. Of the Crude Salt, which groivsfrom the Stone-powder 

 dejected by the said Brines in Boiling. Of the Specific Difference betwixt Sea- 

 Salt and common Salt. A way (which seems to be the true Method of Nature) 

 of Distilling Sweet and Fi'esh Water from Sea fVater, by the Breath of Sea 

 Plants grooving in it. That this Breath probably is the material Cause of the 

 Trade or Tropic JVinds^ In a Letter to the Editor from Dr. Martin Lister.* 

 N° 156, p. 480. 



Notwithstanding the great affinity between the salt of the Midland brine-pits, 

 which is common salt, and the sea salt, I must not omit, among others,-|- a 

 specific difference, which is now first published, and which, in my opinion, makes 

 the sea water a water of its own kind; and also shows that none of the pro- 

 ductions of incinerated plants are truly a marine salt. 



The angles of the crystals of common salt, boiled out of the midland brine- 

 pits; as also of sal gem or rock salt, which I take to be one and the same, are 

 entire, and so are all those lixiviated-marine salts, so called and described by 

 Dr. Grew. But some of the angles of the crystals of true sea salt are always 

 cut off into triangular planes, at least on one of the sides. And this I learnt by 

 suffering a bottle of sea water, taken up on the coast at Scarborough, where no 

 river enters it, to evaporate leisurely, placed in the shade, after it had been" half 

 boiled away : and here all the crystals, which were many, and of different mag- 

 nitudes, agreed in a like figure, as is described. This experiment I repeated 

 with the like success ; and do not doubt but it will succeed with any sea water, 

 brought from any other part of the world. 



Probably the sea-water was the only element of water created at the begin- 

 ning. And the congregation of the waters was called sea. Genesis 1 ; that is, 



• There is nothing in Dr. Lister's observations on the salt springs ofWorcestershire, Staffordshire 

 and Cheshire, or in his conjectures respecting the cause of the trade-winds, worth preserving. The 

 only parts of this paper entitled to notice are those which relate to tlie crystallization of sea salt, and 

 to the distillation of sweet or fresh water from sea water. 



f N. B. The inland brine pits yield not bittern, of which see Mr. Collins, p. 54. — Orig. 



