Description of a Lake of Suiphurie Acid. 187 
pled, which will certainly happen, because the soil is very 
fertile, the drainings which are going on will banish. the 
insalubrity, which T aseribe entirely to the exhalations from 
putrid vegetables which rise from these vast and humid 
forests. In this event, interest alone will induce the inha- 
bitants around to extract the sulphtr from the volcano ; and 
a great portion of the sulphuric lake might even be drawn 
off by rectifying and separating the differentacids contained 
in the water. 
The Javanese have no tradition of recent eruptions from 
this voleano: the convulsions, as I have already remarked, 
have probably been more considerable to the westward. 
We find at Parassane, upon the road from Bagnia-Vangné 
to Batiol-mati, about a league and a half from the sea, and 
to the northward of Mount Idienne, voleanic rocks which 
appear to me to have been a half-melted lava, containing 
several pumice or vitrified stones, which form a kind of 
pudding stone with it. These rocks appear to me to form 
part of a torrent of lava which has descended from the 
yolcano, and which by subsequent deposits has been in a 
great measure covered. 
The Javanese say that thirteen years ago there was an 
eruption which issued with great noise from the east side 
of the summit of Mount Idienne. By an interior cont 
motion, but without any fire or smoke, there was detached 
a great number of rocks, which rolled down to the séa, car- 
rying all before them. A part of this eruption stopped on 
the sea-shore at the place called Klata, about a league to 
the northward of Bagnia-Vangni: here there was 2 moving 
morass, which rendered the road very dificult. The ereption 
overwhelmed it, rendered it stationary, and cooped up its 
waters in a bed which they formed to the northward of the 
place where they formerly were. 
A lake of sulphuric acid of such an extent, found at 
the bottom of a Solfaterra, being a new fact in geology, I 
brought with me to France a bottle full of the water of 
this lake, and M. Vanquelin was kind enough to make the 
following analysis: 
1. The liquor has an acid and at the same time a bitter 
taste, 
2. Its specific gravity is to that of water as 1°118 i8 to 
1900: it marks in the areometer eight degrees. 
3. When evaporated, vapours of muriatic acid and of 
sulphurous acid arise; the liquor takes a yellow colour, and 
deposits some particles of sulphur. . 
4. Upon cooling, this liquor deposited crystals of sil 
; phate 
