52^ PHILOSOPHICAL TRANSACTIONS. [aNNO 1748. 



water of their salt springs into white salt. But in other parts of Europe, as in 

 Britain, and in the northern parts of France and Germany, an erroneous opi- 

 nion long prevailed, that the heat of the sun was not there sufficiently intense, 

 even in the summer season, to reduce sea-water, or brine, into bay-salt. And 

 all arguments would probably have been insufficient to remove this prejudice 

 from the English, had not the contrary been fully proved by experiments, which 

 were first accidentally made in Hampshire. However, the method of making 

 salt by coction will probably still continue to be practised in Britain ; as the salt 

 so prepared is for several uses preferable to bay-salt ; and when prepared after 

 a particular manner, is preferable to common baj -salt, even for curing provisions, 

 as the practice of the Hollanders sufficiently testifies. 



White salt, as it is prepared from various saline liquors, may therefore be dis- 

 tinguished into the following kinds : 1 . Marine boiled salt, which is extracted 

 from sea water by coction. 2. Brine or fountain salt, prepared by coction from 

 natural brine, whether of ponds or fountains. 3. That prepared from sea water, 

 or any other kind of salt water, first heightened into a strong brine by the heat 

 of the sun, and the operation of the air. 4. That prepared from a strong brine 

 or lixivium drawn from earths, sands, or stones impregnated with common salt. 

 5. Refined rock salt, which is boiled from a solution of fossil salt in sea water, 

 or any other kind of salt water, or pure water. 6. Lastly, salt upon salt, which 

 is bay-salt dissolved in sea water, or any other salt water, and with it boiled into 

 white salt ; and under these heads may be ranked the several kinds of boiled salt 

 now in use. Our author has given us an exact history of the manner of pre- 

 paring these different kinds of salt, as practised in different places, with miscella- 

 neous observations and cautions relating to their respective processes. 



From the process by which white salt is made from sea water by coction, it 

 appears, that sea water, besides common salt, contains several other ingredients ; 

 some of which are separated before the common salt falls, and others remain in 

 the bittern, after all the salt is extracted. Our author has given a full and cir- 

 cumstantial account of these in an express chapter, under the appellation of me- 

 moirs for an analysis of sea water. 



The salt-boilers, and particularly those who prepare brine salt, have long been 

 accustomed to make use of various substances, which they call additions or sea- 

 sonings, and mix them with the brine while it is boiling, either when they first 

 observe the salt begin to form, or else afterwards during the time of granulation. 

 These additions they use for various purposes. First, to make the salt grain 

 better, or more quickly form into crystals. Secondly, to make it of a small 

 fine grain. Thirdly, to make it of a large firm and hard grain, and less apt to 

 imbibe the moisture of the air. Fourthly, to render it more pure. And lastly, 

 to make it stronger, and fitter for preserving provisions. 



These additions are wheat-flour, resin, butter, tallow, new ale, stale beer. 



