324j Professor Forbes"'s Account of 



two parallel artificial hedges of black thorn stacked in hori- 

 zontal layers, each hedge being on an average S5 feet high, and 

 {3J feet thick. These sheds {Gradirhduser\ containing double 

 hedges, are no less than Q^^^^ feet in length, or near a mile 

 and a quarter. A wooden trough is carried along the upper 

 part of each thorn hedge {Dornenwand)^ into which the spring- 

 water is pumped. Cocks are placed at intervals of 4 feet in 

 these troughs, which convey a regulated supply of water into 

 small wooden gutters 4 feet long, with narrow slits in the sides, 

 through which the water trickles upon the bed of twigs below. 

 Having dropped through 25 feet of thorns, it is received in a 

 wooden box placed at the bottom, from which it is pumped up 

 to the top of the next adjacent section of the building, through 

 which it again drips, giving off to the atmosphere a fresh portion 

 of its pure water, and this operation is repeated five times. 

 During this process, much solid matter is accumulated on the 

 thorns, which after a year or two become thickly incrusted with 

 carbonate of lime. Nearly all the oxide of iron contained in the 

 water is deposited during the jftrst fall, and marks those hedges 

 with its characteristic ochreous colour. It is a mistake to suppose 

 that the use of all this complicated apparatus is to free the 

 water from the small quantity of earthy matter which it contains: 

 it is solely for the purpose of economizing fuel. The value of 

 the process may be judged of from the fact, that after six falls 

 properly conducted, the brine contains ITJ per cent, of salt, 

 instead of 2|. To obtain this effect, the supply of water must 

 be nicely proportioned to the fitness of the atmosphere for the 

 process of evaporation (Gradirung), 



From 26000 to 28000 hundredweights of salt are extracted 

 from the brine, which has undergone this operation,* or even 

 30,000.t What a vast charge of water the atmosphere hascarried 

 off by this easy process ! By the analysis, we see that 14 grains of 

 muriate of soda are combined with 976 of water, or 70 times 

 its weight ; hence, besides all loss in manufacturing, 210 mil- 

 lions of pounds of water are annually disposed of; and since 



* Maas, Kissingen und soine Heilquellen, Wurtzburg, 1830, p. 38. 

 tPickel,p. 11. 



