MAN D FACT U RE OF SALT. 



117 



their high price would prevent their general introduction. All things taken into the account, 

 if a precipitant is necessary or desirable, pure lime, used in the manner and with the precau- 

 tions heretofore given, will probably be preferable to all others. 



To the question which is so frequently asked. How can the manufacture of the fine salt be 

 improved ? I can answer only in general terms, by imitating as closely as possible the processes 

 observed in the coarse salt fields. This should be the standard, for here salt is obtained in 

 the purest form, and yet by operations entirely simple, and easily varied to suit particular 

 cases. In applying these principles to the manufacture of fine salt, it cannot be too strongly 

 urged, that the first purification of the brine, or the separation of the less insoluble impurities 

 which subsequently form the pan scale, should be effected in vessels (whether reservoirs or 

 pans) other than those in which the salting is to take place. A want of attention to this point 

 is, in my opinion, one of the principal causes of the complaints which have been made in re- 

 gard to this salt. Indeed, the condition of the kettles, containing, as they often do, a deposit 

 of these impurities of three or four inches in thickness, on which the salt is deposited, and 

 from which it is removed by simple ladling and drainage, forcibly exhibits the objections to 

 which this mode of manufacture is ordinarily exposed. 



Another objection to the fine salt, as it is often manufactured at the Onondaga furnaces, is, 

 that it is wet, and forms into solid masses which can with difficulty be removed from the bar- 

 rels into which it has been packed. Its weight is thus almost fraudulently increased, and its 

 value for various purposes seriously impaired. This arises from the want of care in removing 

 the bitterns, a term applied to designate the highly deliquescent chlorides of calcium and 

 magnesium. These substances, in consequence of their great solubility, remain with the salt; 

 and the drainage to which it is subjected after being taken from the kettles, is intended to 

 effect their removal. But oftentimes this drainage is not sufficiently long continued ; and the 

 result is, that these deliquescent substances are still in a great proportion mixed with the salt. 

 The separation of these might perhaps be more advantageously and completely effected by 

 putting the salt into a vat having a double bottom, and pouring on it small quantities of cold 

 water. Performing this operation, if necessary, two or three times, the bitterns or easily so- 

 luble matters would be carried off,  while the pure salt would remain ; a very small portion 

 only of which would be dissolved. I am satisfied that a strict attention to the two points 

 above noticed, viz. the separation of the less soluble materials in vessels other than those in 

 which the salting is effected, and the Qomplete removal of the bitterns by drainage or washing, 

 would entirely remove the objections which have heretofore, with too much truth, been urged 

 against the Onondaga fine salt. 



I have only to add to the remarks which have already been offered, that several manufac- 

 tures, in which common salt is employed, might be advantageously carried on in the vicinity 

 of our brine springs. Among these are the soda ash, or British barilla, which is now so ex- 

 tensively used in the manufacture of glass and soap ; the various preparations of soda for 

 medicinal use ; and the chloride of lime, of which large quantities are consumed in the process 

 of bleaching. The manufacture of sulphuric acid, or oir of vitriol, might perhaps be as well 



