VOL. XLV.] PHILOSOPHICAL TRANSACTIONS. 523 



bottoms or lees of ale and beer, wine lees, and alum. Wheat-flour and resin 

 are used for the property they possess of making the salt a small grain. Butter, 

 tallow, and other unctuous bodies are commonly applied, as they are said to 

 make the brine crystallize more readily ; for which end some salt boilers more 

 particularly prefer the fat of dogs : but others have little to plead for their using 

 these substances, but immemorial custom : how far they have the effects ascribed 

 to them can only be determined by experiments, as several boilers, who formerly 

 used them, now find they can make as good salt without them. Wine lees, new 

 ale, stale ale, the lees of ale and beer, are now generally rejected by the marine 

 salt boilers ; except in the west of England, where the briners, who use them, 

 affirm that they raise a large grain, and make their salt more hard and firm, and 

 some say that they make it crystallize more readily. Hoffinan prefers the 

 strongest ale ; and Plot assures us, that it makes the salt of a larger or smaller 

 grain, according to the degree of its staleness. The only good efiects that fer- 

 mented liquors can have as an addition, are probably owing to their acid spirit, 

 which may correct the alcaline salts of the brine, and so render the common salt 

 more dry and hard, and less apt to dissolve in moist air. If therefore it should 

 be thought necessary to use any of these additions, in order to correct the alca- 

 line quality of the brine, stale ale, or Rhenish wine,* ought to be chosen, as 

 new ale contains but little acid. 



Alum is an addition long known and used in Cheshire, together with butter, 

 to make the salt precipitate from some sorts of brine, as we are assured by Dr. 

 Leigh in his Nat. Hist, of Lancashire, Cheshire, &c. who first taught the 

 Cheshire salt-boilers the art of refining rock salt. As the bad properties of their 

 salt proceeded from hard boiling, they found every method ineffectual, till they 

 had recourse to a more mild and gentle heat. And as alum has been long dis- 

 used among them, it is not likely that they found any extraordinary benefit from 

 it ; otherwise they would scarcely have neglected it, and continued the use of 

 butter. However Mr. Lowndes has lately endeavoured to revive its use ; assert- 

 > ing, that brine-salt has always 2 main defects, flakyness and softness ; and to re- 

 medy these imperfections, he tried alum, which fully answered every thing he 

 proposed ; for it restored the salt to its natural cubical shoot, and gave it a proper 

 hardness ; nor had it any bad effect whatever. But our author is of opinion, 

 that whoever considers the nature of alum, will scarcely expect such extraordi- 

 nary effects from it. Neither does it here seem wanted ; for the grains of com- 

 mon salt will always be sufficiently hard, and of their natural figure, large size, 

 and no ways disposed to run by the moisture of the air, if formed by a gentle 

 heat, and perfectly free from heterogeneous mixtures : so that the goodness of 



* Why not malt-vinegar ? CM. — Orig. 

 3x2 



