412 Abstract Report of Agricultural Discussions. 



quality, but that new blood must be got to maintain size. He considered 

 the use of swedes for ewes just after lambing to be a dangerous 

 practice. They should not be had recourse to until the whites are 

 done. It is good management to give these turnips on grass, and to 

 let them " welt," or become dry from exposure to the sim and air ; 

 indeed, but for the game, he should hardly ever put roots into " pics," 

 for he had known large uncovered heaps of white turnips keep good 

 till April. He would make no other suggestion in reply to Colonel 

 Challoner's second inquiry, but that cako and corn must be used in 

 moderation. 



Meeting of Weeldy Council, Wednesday, March 29///. The President, 

 Sir E. Kerrison, M.P., in the chair. A Lectiiro was delivered by 

 Dr. VoELCKER on 



Natural Deposits of Potash in Germaxt. 



Dr. VoELCKER said : Next to phosphoric acid, potash is unques- 

 tionably the most important mineral constituent of the ashes of plants. 

 It is important for a variety of reasons. First, because it is found in 

 a preponderating quantity in all such ashes. Next, because it facili- 

 tates the assimilation of a variety of other mineral matters which aro 

 carried into the vegetable organism in the shape of potash salts — a 

 class of salts which is not distinguished, generally speaking, by great 

 solubility. We have strong reason to believe that, in the shape of 

 silicate of potash, silica, so largely required by all cereals, is carried 

 into the vegetable organism. 



Hitherto potash has been obtained mainly from the ashes of plants, 

 Russia and North America having furnished our supplies. Potash, or 

 rather carbonate of potash, is kno\ATi by the name of vegetable alkali ; 

 and the very name implies that it enters very largely into the com- 

 position of all vegetable substances. Recently however — that is, 

 within the last five years — new sources of potash have been discovered 

 in Germany, in an extensive salt-mine explored about 1851. The salt- 

 mines to which I now refer are of great national importance to Prussia ; 

 they occur in the neighbourhood of Stassfurth, a place about ten 

 English miles from Magdeburg, and are so extensive, that persons who 

 are well entitled to express an opinion on the subject, describe the 

 mines of Stassfurth as vicing in importance with the celebrated 

 salt-mines of Galicia, those of Bohemia, and those of Wieliczka, which 

 are of such great national importance to Austria. Now, it is in these 

 salt-mines that the natm-al deposits to which I allude, in the shape of 

 a variety of crude salts of potash, are foimd. 



On account of the agricultural importance of these potash-salts, I 

 visited, last autiimn, in company ^^•ith Dr. Gilbert, the salt-mines of 

 Stassfurth. I descended them, so as to obtain an idea of the 

 extent of the natural deposits, and I was highly impressed with their 

 importance, as well as charmed with the appearance of the enormous 

 masses of almost chemically-pure rock-salt. 



The salt there, as in so many other places, occurs in the new red 

 sandstone formation. The surface consists of alluvial deposits, which 



