Lenkey - with a temperature of 22.5 centigrades and a high content of iodine, is recommended for treatment of eyes and the thyroid gland. In the past its fumes caused sudden deaths of birds and animals in the vicinity. Before surface modifications were carried out, the fumes were highly toxic and hazardous, as the spring was gushing out in the enclosed space of a small cave, producing a strong concentration of carbon dioxide. The spring was eventually altered in 1834 by Acacius Lenkey, a natural scientist and admirer of the Sliač nature.