414 Abstract Report of Agricultural Discussions. 



combination of cliloride of potassium, or muriate of potasli, as it is 

 called in commerce, with chloride of magnesium and water. Its 

 composition is as follows : — 



Chloride of magnesium 31'4() 



Chloride of potassium 2-i'27 



Chloride ot sodium ij'lO 



Chloride of calcium 2'62 



Srdphate of lime 0-84 



Oxide of iron 0"14 



AVater 35-57 



100-00 



It is a definite chemical combination of 1 equivalent of chloride of 

 j)()tassium, 2 equivalents of chloride of magnesium, and 12 of water. 

 In some layers this caruallitc is of a beautiful rose colour ; in others 

 it is of an intensely blood-red colour. 



Besides the caruallite, we have several otlier minerals in the salt 

 deposits. One of a yellowish colour is a salt which, (m exposure to 

 the air, runs at once into a liquid. On this account it has been called 

 tachhydrite. This is a comldnation of chloride of calcium with chloride 

 of magnesium and water. Then we liave another description, which is 

 of a wliite appearance — boracitc, containing l)oracic acid. These salts 

 are of great scientific interest, because they throw light on the manner 

 in which these extensive salt-mines — mines which are believed to extend 

 over a surface of at least 18 geographical miles, and perhaps to connect 

 some of the salt-deposits in Wurtemberg ^\-ith tliose of Prussia — were 

 deposited. 



I have before me a highly interesting work on these salt-mines 

 by Dr. Eeichardt, Professor of Mineralogy and Chemistry in the 

 University of Jena, in which he points out that these salt-deposits 

 are identical with the salts in the motherlays of ordinary sea-water. 

 After the ordinary pure commtm salt has been separated fi-om these 

 lays, there remains a liquid wliich crystallizes only on the appli- 

 cation of a large amount of heat ; and this liquid contains the identical 

 salts which are here deposited above tlie pure rock-salt. We also find 

 in these crude salt-deposits bromine, which is a well-kno'mi constituent 

 of sea-water. Indeed, these salts smell of sea-water — so much so, as 

 to make you fancy that you ai-e in the neighbourhood of the sea-shore. 



I now pass on, in order to bring more prominently before youi" view 

 tlic agricultm-al bearing of the products which are now manufactured 

 at Stassfm-th from these skim-salts. For several years after the mines 

 were discovered, the skim-salts were throANTi aside, no use having 

 l)cen found for them. They, however, interested the scientific inquirer, 

 who was struck with the large, though varying j^roportion of potash 

 found in them. I have here two analyses to which I will now merely 

 allude, my object being that you may see the variations in the amount 

 of salt-deposits, and more especially in the amovmt of i)otash. Sufiice 

 it to say, that the chloride of potassium amounts on the average to 

 IS per cent. There is mixed with this 22 per cent, of chloride of 

 magnesium, 10 per cent, of sulphate of magnesia, 3 per cent, of 



