No. 108.] 59 



The withdrawing annually from beneath the surface more thaft 

 three millions of bushels of solid substance, must make a mighty 

 void to be filled with air or water somewhere, unless the earth settles 

 down and fills the space; it therefore becomes important to determine 

 w^here the fossil salt liesj for if it should be found to compose the 

 under stratas on which these towns I have named are so rapidly build- 

 ing, when these become one great city, the increased weight ujion 

 the surface may be too great for the support which may be under- 

 neath, and the whole give w^ay and make another lake. This may 

 be said to be speculation, but there are reasonable grounds to found 

 such a speculation upon. At Syracuse, where the under strata is 

 sand and gravel, this cannot be feared, for the reason, that fossil salt 

 cannot repose in a bed of sand gravel; it is an unnatural position, 

 and one which it is impossible it could long occupy, in a country 

 where great quantities of water fall from the clouds upon a surface 

 which absorbs it. 



The Onondaga salines can be made to furnish salt water sufficient 

 to manufacture ten millions of bushels of salt per annum. 



The water, as I before remarked, is from 78 to 81 degrees of 

 strength as denoted by the hydrometer, which is graduated at O for 

 fresh water, and 100 for water fully saturated with salt. 



Should the State authorities make such arrangements as will result 

 in the condensing the salt water by artificial heat to near the point 

 of saturation, the impurities in the water, which are very trifling, 

 would be precipitated, and the pure brine would then be used in all 

 the vats, which are three in a set, instead of one. The manufac- 

 turers ot solar salt use one vat to precipitate the earthy matter, a se- 

 cond to throw down the sulphate of lime, and the third to crystalize 

 the salt. In the event of first condensing the water by artificial heat, 

 three times the quantity of salt could be crystallized in the same vats; 

 but a large number of large deep vats would be necessary to receive 

 the brine in which the impurities must be precipitated from the boilers 

 heated by terrestial fire. The result of such a process is a matter of 

 mathematical calculation as to profit; its practicability as a chemical 

 operation is unquestionable. The operation of heat has the efiect to 

 cause all earthy particles which are held in suspension in the brine 

 to precipitate, and the concentrating or condensing the salt water to 

 that point at which the impure salt crystallizes, and allowing the 

 fluid to remain quiescent for a few days, the operation of crystalliza- 

 tion of the more easily crystallized salts will be completed. 



Thomas Spencer, Esq. the State superintendent of the Onondaga 

 Salines, in a letter which he addressed to the editors of the Journal 

 of Commerce on the 29th of July, 1842, and which was published 

 in that paper on the 2d of August, states that the vats for solar evapo- 

 ration to cover an acre of ground cost about $1,200, and that one 

 man can attend two acres. One acre will produce on an average 

 about two thousand bushels of solar salt annually. 



If all the salt manufactured in kettles, &c. at the Onondaga Sa- 

 lines, in 1841, had been produced in vats, it would have required as 

 many as would cover sixteen hundred and sixty-seven acres of ground. 



