_It contains a small quantity of chalk, common salt, and carbonat of soda (201), the latter of which renders it soapy to the touch. But the most striking feature in this water is_ _the unusual quantity of sulphur which it contains; and which is so extremely volatile on the application of heat, that none of it is left in the residuum after evaporation. In this water there is also a considerable portion of carbonic acid._ The city of Aix─la─Chapelle is in the circle of Westphalia, betwixt the rivers Meuse and Rhine, about seventy miles east of Brussels, and in a rich and fertile country. Its waters have been in great medical repute, and have attracted a numerous concourse of visitants for many centuries past. Their reputation was so well established, even in the time of Charlemagne, that he frequently resided at Aix: and he is said to have been so much delighted in the use of the waters as to have sometimes even held his levee at the baths. In this city, and in the small territory that belongs to it, there are several sources of hot water. Of these the principal spring is enclosed in a stone cistern, which is vaulted and almost conical at the top, and the parts of which are connected with the utmost care, to prevent the vapour from escaping. From this spring the water flows, in a copious stream, into several spacious and elegant baths, in the different parts of the city, distinguished by the names of the Emperor’s Bath, the Nobles’ Bath, the Poor’s Bath, and other appellations. In most of these there is every necessary apparatus for bathing by immersion, for vapour bathing, and for pumping on any particular parts of the body. The water rises, with great quickness, from the springs, and sends forth bubbles of air, which burst with a slight noise when they reach the surface. It is at first perfectly colourless and pellucid, and emits a large portion of steam, and with it a strong sulphureous smell, which is perceptible at a great distance. Its temperature is so high, that, in the large baths, it requires to stand from fifteen to eighteen hours before it is sufficiently cooled for tepid bathing; and it is one of the few natural springs which are hot enough to be employed as a vapour bath without the addition of artificial heat. On standing to cool, it gradually loses its clearness, acquires a milky hue, and deposits an earthy sediment, which is entirely calcareous. At the same time it loses its offensive smell, and, when cold, has scarcely any odour. Wherever a large quantity of this water passes hot from the spring through a confined place, the upper covering becomes encrusted with sulphur. This is particularly the case with respect to the dome of the vault that encloses the great source which supplies the Emperor’s bath, and which is opened, from time to time, for the purpose of having the sulphur brushed off.