28 HOW IS SALT PROCURED? 



More frequently it is procured by the evaporation of sea-water. Great 

 quantities are thus made in England, Scotland and in our own country. 



Subterranean saline springs furnish the principal supply for Germany. 

 In most of the larger states these are found and some of them have been 

 known and used for a thousand years. Near Gnadau not far from the 

 fortress of Magdeburg, in Prussia, there is such a salt spring of great 

 value. The water is raised to the surface of the ground by steam; but 

 as it does not contain more than ten or twelve per cent of salt, and holds 

 several other mineral substances in solution, it must undergo a filtration 

 before it is fit for evaporation. For this purpose faggots are piled up in 

 immense numbers, forming a rampart a mile and a half long, fifty feet 

 high, thirty feet wide below and twenty at the top. The salt-water, after 

 being collected in reservoirs above ground, is elev^ated by a windmill to 

 the summit of this long pile at its upper end. It is there discharged into 

 a trough four feet wide and deep that runs along the top. This is sup- 

 plied with stop-cocks along both sides, through which the water is let 

 out to trickle down through the faggot pile. As it drips from twig to 

 twig, and is thus completely exposed to the air, much of the water is 

 thus spontaneously evaporated and a thick coating of carbonate of lime 

 deposited upon the faggots. These soon become clogged with incrusta- 

 tions of lime and salt and are then removed and pounded up for manure, 

 their place being supplied wiih fresh ones.* When the water has trickled 

 down through the pile and been received there into the wide troughs that 

 accompany it during its whole length, it is found to be considerably in- 

 creased in saltness, but several more filtrations are still necessary to give 

 it the requisite proportion of salt, viz: twenty-six per cent. It is there- 

 fore raised again by another windmill (twelve of which stand along the 

 top of this singular pile, like sentinels upon a rampart) and made to un- 

 dergo a second, and third, and fourth, exposure to the air in its down- 

 ward progress through the faggots. Reaching at length the end of this 

 huge filtrating appai-atus, and having gained its required percentage of salt, 

 the brine is now received into iron pipes that convey it under gi-ound two 

 miles to the river Elbe, on the banks of which stand the extensive build- 

 ings that contain the cauldrons for evaporating it. The reasons for con- 

 veying it to the river no doubt are, the convenience of the fuel there and 

 the ease of transportation. 



Similar springs, though far richer, have given name and wealth and 

 population to Ilalle, in Prussian Saxony — (Halle from uX<;=salf.) The 

 saline springs here were known to the Romans, and have seasoned the 



* Specimens of this incrustation may be seen in the Cabinet of the Linnseau 

 Association of Pennsylvania College. 



