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from numerous explosive eruptions may be summarized as follows. 
After each eruption during an average period of rest of 18 years’) 
the crater is after about six years filled up with rainwater. 
Hence the new explosive eruption must take place through the 
water of the crater lake, so that this is blown out of the crater 
mixed with hot ash, pumice and voleanic bombs and lapilli all 
of which flow down the slopes of the voleanic cone as a hot mud 
flow, which is known as a “lahar”’ (hot lahar) by the Javanese people. 
Eruptions of the Klut-voleano are known to have taken place in 
1586, 1752, 1771, 1811, October 11—14% 1826, 1835, May 16% 
1848, January 4% 1864, May 22'>—23'h 1901 and May 19%—20 1919. 
In 1875 without any volcanic action the west side of the rim 
erumbled away, by which the crater lake was partially emptied 
and cold lahars were formed. 
When the eruption lasts longer than the time necessary to blow 
out all the water from the crater lake, there follows upon the hot 
lahars an ordinary ash-rain. Still later cold lahars follow in conse- 
quence of the abundant tropical rainfall. 
The section of deposits which results from the above sequence 
would comprise in order from above downward: 
III. Tuff from cold lahars in consequence of heavy rainfall. (Trans- 
posed material from I and II). 
II. Ash, deposited as subaérial sediment. (Second eruption-sediment). 
I. Tuff from hot lahars. (First eruption-sediment). 
It is remarkable how much heat remains in such a lahar after 
the water has partly drained away and in part evaporated. After 
the eruption of 1919 KemmerriNe (lit. 14) observed in numerous 
places pseudo-voleanic phenomena, caused by the water evapo- 
rating in the lahar’). VrissrriNG (lit. 11 p. 73) mentions that 
a walking-stick which four days after the eruption of 1901 was 
poked into the lahar, was drawn out in flames. KEMMERLING mentions 
(lit. 14 p. 811) that some days after the eruption he measured a 
temperature of 360° C. in a gas-emanation on the lahar. March 25th 
1921 I visited the Klut and Mr. G. K. R. HöJcaarp, topographer 
to the Netherland East Indian Mining Service (Mijnwezen) told me 
that the temperature of the lahar of May 1919 still amounted to 
178° C. at a depth of 50 cM. 
The final account of the Klut eruption of 1919 by the voleano- 
1) This average is computed from the eruption dates since 1811. 
_® A splendid photograph of the lahar of 1919 with steam clouds is to be 
found on pp. 116—117 of the well-known French Weekly „Illustration” of 
Aug. 9th 1919, No. 3988. This picture was taken on May 22th 1919. 
