1 10 Analysis of several Varieties of 



Through these it drains into pits made under ground, which 

 leceive the liquor called bittern or bitter liquor. Under* 

 the troughs, and in a line with the holes, are fixed upright 

 stakes, on which a portion or* salt that would otherwise 

 have escaped, crystallizes and forms, in the course of ten 

 or twelve days, on each stake, a mass of sixty or eighty 

 pounds. These lumps are called salt cats. They bear the 

 proportion to the common salt, made from the same brine, 

 of one ton to 100. 



From the mother brine or bitter liquor, which has drained 

 into the pits, the sulphate of magnesia is made during the 

 winter season, when the manufacture of salt is suspended, 

 in consequence of the want of the temperature required 

 for the spontaneous evaporation of the sea water. The pro- 

 cess is a very simple one*. The bitter liquor from the pits 

 is boiled for some hours in the pans, which are used in sum- 

 mer to prepare common salt ; and the impurities, which 

 rise to the surface, are removed by skimming. During 

 the evaporation, a portion of common salt separates; and 

 this, as it is too impure for use, is reserved for the purpose 

 of concentrating the brine in summer. The evaporated 

 bitter liquor is then removed into wooden coolers eight feet 

 long, five feet wide, and one foot deep. In these it re- 

 gains twenty- four hours, during which time, if the wea- 

 ther prove clear and cold, the sulphate of magnesia, or 

 Epsom salt, crystallizes at the bottom of the coolers, in 

 quantity equal to about one-eighth of the boiled liquor. 

 The uncrystallizable fluid is then let off through plug-holes 

 at the bottom of the coolers; and the Epsom salt, after 

 being drained in baskets, is deposited in the store-house. 

 This is termed single Epsom salts, and after solution and a 

 second crystallization, it acquires the name of double Ep- 

 som salts. Four or five tons of sulphate of magnesia are 

 produced from a quantity of brine, which has yielded 100 

 tons of common, and one ton of cat salt. 



On the banks of the Mersey, near its junction with the 



#* ! am indebted for an account of this process, as well as of the method 

 «f making common salt at l.ymington, to the liberal communication of 

 Charles S;. Barbe, esq. of that place. Though not strictly connected with 

 the subject, I give his description of the mode of making Epsom salt, be- 

 cause no correct statement of the process has, I believe, been hitherto pub- 

 lished. The analysis of sea water, indeed, by a jur-tly distinguished chemist 

 (Bergman), excludes, erroneously, the sulphate of magnesia from its com- 

 position , and his results have led to the opinion, that to manufacture this 

 $alt on the iarge scale, requires the addition cither of sulphuric acid, or of 

 same sulphyfe to' the L-UUr liquvr. ("See Aikin's Chemical Dictionary, ii. 



Irish 



