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than that in which it naturally occurs. This does away with the inconvenience of having it crumble. Such bricks are considerably used in France and Belgium for railroad and other purposes.

3. Lignite of a black color, in a finely powdered state, has been used in England, under the name of "Cologne Earth," as the basis of a black paint.

4. Lignite has been successfully used in place of bone-black in clarifying sugar.

MINERAL SPRINGS.

Springs are of very frequent occurrence throughout East Texas. Somethey are very pure, and almost entirely free from any mineral matter, while at other times they are highly charged with iron, sulphuric acid, and salts of lime, magnesia, alumina, and alkalies. Iron springs, however, are by far the most plentiful of all the mineral waters, and it is an exceedingly common occurrence to see chalybeate waters arising from Tertiary strata. The interstratification of sand and clay beds, representing as they do alternate permeable and impermeable layers, is peculiarly favorable to the existence of local springs. Water falls on the sandy surface of a hill and runs down between the loose materials until it meets a clay bed. This proves impassable on account of its impervious nature, and the water, thus deflected from its downward course, runs over the surface of the clay until it reaches the outcrop of the bed in a hillside or river bluff, and here gushes out as a spring. The ferruginous springs derive their iron from the beds through which they pass. The sandy soils are often bleached on the surface, while "

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Compare First Report of Progress Geological and Mineralogical Survey of Texas, 1888, p. 20.