MECHANICS AND USEFUL ARTS. 109 



A good portion of the coarse hard salt imported into the United States 

 from the most southerly islands of the West India group, is kiln dried, 

 cleansed, ground very fine, and put in small packages for culinary or dairy 

 use. The amount of coarse and fine salt imported into the United States 

 from foreign countries dui'ing the year ending June 30, 1856, was 15,405,864 

 bushels. The amount of domestic salt exported during the year ending 

 June 30, 1856, was 698,458 bushels. The amount of foreign salt exported 

 during the year ending June 30, 1856, was 126,427 bushels. 



IMPROVEMENT IN THE MANUFACTURE OF SALT. 



Where artificial heat is employed to produce salt, the brine is placed in 

 large kettles, and the fire applied beneath. After the brine has become re- 

 duced to what is called " strong brine," and begins to crystallize, it is liable 

 to cake up and collect on the bottom of the kettle. It is in part kept clear 

 by attendants, who stir up the mixture, scrape it off, etc. But in nearly all 

 cases there is some caking and a partial discoloration of the salt, which tends 

 to diminish its selling value. 



An improvement, patented by J. P. Hale, of Kanawha, Ya., consists in. 

 the use of two kettles placed one inside the other, a space being left be- 

 tween. The weak brine is boiled in the lower kettle against which the fire 

 is applied. After the liquid has boiled down into " strong brine " it is drawn 

 off into a vat, where it remains long enough for its impurities to settle. It 

 is then pumped into the tipper kettle and crystallized, no stirring being re- 

 quired, as no caking or discoloration occurs. The upper kettle is heated by 

 the hot brine between it and the lower vessel. 



Mr. J. L. Humphrey, of Syracuse, N. Y., has invented an improvement 

 in Salt Evaporators, which consists in an arrangement whereby the heated 

 products of combustion from a furnace are drawn, by a blower, through flues 

 passing through a closed evaporation vessel below the surface of brine, or 

 other liquor, and by the same blower are forced back again, through the ves- 

 sel, over the surface of the liquor, and into the chimney of the furnace. The 

 heat from the furnace is thus used to effect evaporation both below and above 

 the surface of the liquor, and the draft of the chimney is employed to carry 

 off the evaporation. The improvement consists, further, in a scraper fitting 

 to the flues below the surface of the liquor, and having a movement back 

 and forth along the tubes, to remove the deposit which is caused to incrust 

 itself upon them by crystallization, and which, if not removed, would pre- 

 vent the heat being rapidly conducted to the liquor. 



IMPROVEMENTS IN APPARATUS FOR SOLAR EVAPORATION. 



An improved arrangement for evaporation by solar heat, recently patented 

 by Mr. Gordon, a distinguished engineer of London, consists in employing 

 reflecting apparatus, or concentrating or refracting lenses, or both combined, 

 in such a manner that the heat of the sun's rays is for hours continuously 

 rendered applicable for purposes of evaporating and even distilling fluids. 

 The apparatus the patentee calls a thermoheliostat, because it collects the 



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