proceedings: Washington academy of sciences 577 



It is a well-known fact that a lava mountain has often been formed 

 by magma squeezed out of the earth's interior in a comparatively 

 quiet way. An interesting instance of this occurred in 1919, when, in 

 a crater of Mt. Galungun, a flat dome 400 meters in diameter and 100 

 meters in height was built up in a period of three weeks. 



Mt. Merapi, now 3,000 meters high, built up repeatedly a heap of 

 lava blocks in its crater, alternately with severe eruptions. The 

 present lava cone began to form in 1883, and has now attained a height 

 of 300 meters. It fills the crater completely, and red-hot blocks are 

 being hurled over its rim and fall down the slopes of the mountain. 



One of the most terrible volcanoes of Java is Mt. Kloot, because it 

 has a crater-lake which has been repeatedly thrown out by the explo- 

 sions of the crater furnace. Thirty-eight million tons of water, mixed 

 with volcanic ash and erosion products of the ravines, flow down to 

 the plains as a terrible mud-stream. This happened four times in 

 the course of the nineteenth century, and again in 1901 and 191 9. 

 Soundings with a maximum thermometer in 191 6 revealed no indica- 

 tion of a rise in temperature, and the native official who visited the 

 lake weekly reported no activity. Shortly after the 1919 eruption 

 an attempt was made to drain the lake, so as to prevent the formation 

 of the destructive mud-stream in case of a future eruption. The boring 

 of a tunnel, at the level of the crater bottom, through the crater wall, 

 has been started, notwithstanding the tremendous difficulties involved. 



Another dangerous crater lake is that of Mt. Idjen, the most easterly 

 of Java's volcanoes. Its water is of great acidity, containing in solu- 

 tion about 6 per cent of hydrochloric acid and about 2 per cent of sul- 

 furic acid, besides many other chemical compounds. The acid stream 

 which drains this lake is neutralized by another containing lime. 

 However, when the lake overflows, the neutralization is insufficient and 

 the acid water does much damage in the coastal plain. A sluice has 

 been built to remedy this evil. Layers of sulfur are found in the crater 

 walls, and natives cross the lake in canoes to dig out the sulfur. In 

 191 6 soundings were made in the lake and its temperature was investi- 

 gated by means of a batho thermograph of new design, by which water 

 pressure and temperature were registered simultaneously. In the 

 central pool, 260 meters in depth, concentrated acid at a tempera- 

 ture of about 100° C. was encountered. The work had to be discon- 

 tinued, however, owing to the loss in the pool of both the thermo- 

 graphs and the maximum thermometer. When new instruments had 

 been made by Dr. J. Boerema, of the Batavia Observatory, renewed 

 activity of the crater prevented the resumption of the work. 



149TH MEETING 



The 149th meeting was held in the auditorium of the New National 

 Museum, October 23, 1920, at 8.15 p. m., the occasion being an address 

 by Dr. E. B. Rosa, of the Bureau of Standards, entitled A reorganized 

 Civil Service. The address was published in the last number of this 



