CHINA, MONGOLIA, AND JAPAN. 



87 



While we were here drops of scalding mud were incessantly thrown out, but 

 regular mud flows appear to be very rare. 



The superintendent of the sulphur works informed me that when new vents 

 open, mud and large blocks of rock are thrown out with much violence. Such 

 blocks cover the interior of the crater, and have been already mentioned ; they are 

 frequently almost entirely decomposed by the action of the gases. 



From an extinct vent I traced a stream of mud, following the bed of a guUy, 

 for several himdred yards. It is hard, compact, and filled with small crystalline 

 needles of sulphur, the longer direction of which was found to be invariably at 

 right angles to the nearest surface, by which either the heat or moisture, or both, 

 escaped. These crystals occur equally distributed throughout the mass the whole 

 length of the stream, and produce, on a small scale, a tendency to columnar struc- 

 ture. They cannot, considering their position, have been crystallized until the 

 mud was quiescent and hardening, and as the solidification depended on the escape 

 of. the moisture that rendered it fluid, it forms, I think, a good illustration of the 

 fact that columnar structure is not necessarily a result of cooling, but rather of the 

 escape of the " vehicle of fluidity," whether this be heat or water, or, as here, both 

 combined. 



The stream in question appears to be the result of a single flow filling the 

 inequalities in the bottom of the gully, and is in places several feet deep. 



The government has large sulphur works on this mountain, with which the pro- 

 duction of alum was formerly combined. The material used, from which the sul- 

 phur is extracted, is the debris formed by the ever-falling walls of the crater, and 

 which is said to contain from 25 to 50, and even 60, per cent, of the mineral, in 

 layers and impregnated through the mass. 



Without further preparation than being broken with the hammer, this raw 

 material is put into three iron pots over a fire. Each of these vessels is composed 

 of two parts, a cylinder and a hemispherical bottom or pot on which it stands, the 

 whole being about two and a half feet deep and two feet in diameter. ' After melt- 

 ing, the impurities seem to settle to the bottom, and the top is ladled out into shal- 



Tltr 12 



Shallow depressions. 



low depressions in the ground. When this is cooled, it is a hardened mud filled 

 with crystals of sulphur in needles, their longer axes at a right angle to the surface 

 of the cooled mass, and the whole product differs from the mud described above, as 



