VARIETIES OF SALT. 23 



whilst in the kettle system the separation and removal of the 

 impurities take place in one common vessel with the making 

 of the salt. The manufacture of boiled salt in hemispherical 

 cast-iron kettles is peculiar to our country ; its success, so far as 

 the quality of our home-made salt is concerned, is more due to 

 our superior qualities of brines, and the skill of the workmen 

 in charge of its manufacture, than to the fact that the mode of 

 making our boiled salt is based, in that particular case, on the 

 safest principle. From the fact that twenty to thirty kettles are 

 placed in rows over one common fire and along one com- 

 mon flue, it will be apparent that the separation of salt must 

 take place within the various kettles at a different rate and 

 under otherwise different circumstances. The salt obtained 

 from the various kettles differs consequently more or less in its 

 mechanical condition and its composition ; the salt obtained 

 from the front kettle is more compact, of a small grain, hard 

 and heavy, whilst the salt made in the back kettles is of a looser 

 aggregation, consequently bulky and light. To secure a desir- 

 able uniformity for commercial purposes, the salt is always mixed 

 in the storehouse before packing. The chemical composition 

 of the boiled salt is, to a large degree, controlled by the same 

 circumstances which have been pointed out in the case of the 

 composition of the coarse qualities of salt. As not two brines 

 are of an entire corresponding composition, there can be no two 

 samples of salt, made from two different brines, alike. All our 

 commercial varieties of salt differ, therefore, somewhat on 

 account of the mode pursued in their manufacture and the na- 

 ture of the saline solutions turned to account for their produc- 

 tion. A good "common fine salt" ought to be of a neutral 

 reaction, of a clear wliite color, of a pure, agreeable saline 

 taste, and of a gritty feeling between the fingers ; it ought to 

 dissolve without any particular residue in five to six parts of 

 water, and its moisture ought not to exceed from four to five 

 per cent. 



Our present demand of salt, which is still almost exclusively 

 confined to its uses for domestic purposes and in agricultural 

 industry, exceeds our production — a fact which is not so much 

 due to a real want of suitable natural home resources as to 

 their disadvantageous local distribution. Whilst the Central, 

 Middle and South-western States are daily increasing their local 



