The salt furnace is one of the most interesting sights around the works, and consists of a series of iron pans, about forty in number, each pan being about three feet wide and ten feet long. These pans rest on a stone wall over a fire pit, and are covered over with a wooden-box chamber about one hundred and twenty feet long and three and a half feet high. This covering is called a steam chest, and, like the lid on a kettle, helps raise the temperature of a solution to a higher point than could be obtained in an open vessel. After the proper boiling has been given to a quantity of the salt solution, it is drawn off into a wood vat, called a mud settler, and, although the solution seemed perfectly clear while entering the heating pans over the furnace, a considerable residue is found at the bottom of the mud settler. This residue contains a large proportion of oxide of iron. From the mud settler the hot solution passes to two vats called drawn settlers, where the solution is still further clarified and treated. The solution then passes to the first graining vat, which is a long wooden box lined with tile, where the salt begins to form in flakes on the surface, and falls to the bottom of the vat, where it is picked up by power scrapers or shovels. The best salt is formed in this first grainer, although different grades of salt are extracted from the solution in five other grainers, and they are used for the feeding of cattle and the making of brine solutions. SPONTANEOUS COMBUSTION. There is undoubted evidence that hay and cotton, when damp, will occasionally take fire without any external source of ignition. Cotton impregnated with oil, when collected in large quantities, is especially liable to take fire spontaneously. Numerous cases are recorded where an accumulation of cotton waste, used in wiping oily machinery, lamps, et cetera, has more than once caused fires and led to unfounded charges of incendiarism. Whether or not such organic substances as damp grain or seeds ever undergo spontaneous combustion is a question that has never been satisfactorily proven, although three French scientists--Chevallier, Ollivier, and Devergie--are authority for the supposition that the burning of a barn investigated by them was caused by the spontaneous combustion of damp oats stored in it. There have been many instances of the spontaneous ignition of coal containing iron pyrites when moistened with water. This is particularly noticeable in coal mined in Yorkshire and some varieties found in South Wales. Phosphorus in a dry state is probably the most quickly ignited substance known. It has been seen to take fire, when touched, in a room in which the temperature was under seventy degrees Fahrenheit. Doctor Taylor, a writer on the principles and practice of medical jurisprudence, is authority for the statement that ordinary phosphorus (blue head) matches have taken fire spontaneously, as a result of exposure to the sun’s rays for the purpose of drying.