710 ON THE VOLCANO OP TAAL, 



Sefior Centeno mentions the mode ia which the phenomenon of 

 ebullition is manifested at this part of the crater. There was a 

 periodical boiling up about the centre of the waters, which were 

 raised for the time being into a kind of jet, from which mud and 

 clay were thrown out with a noise like the boiling of a cauldron. 

 This must be due to a periodical escape of gas, somewhat similar 

 to what is taking place in the smoking craters. 



Green Lake. — At the time of Centeno's visit the green lake was 

 absent or possibly merged in the yellow one, but it was by far the 

 larger in 1885, and in fact the yellow lake seemed only a shallower 

 prolongation of it, with a margin of sulphur and felspathic mud at 

 the time of my visit. The green colour was, as I have said, 

 intensely vivid. The waters were singularly still, but in Centeno's 

 time they were continually emitting sulphurous vapours. The 

 margins were pi-ecipitous on all sides, and higher on the south-east, 

 making it impossible to get near enough, with the means at my 

 disposal, to obtain any specimens of the water. It will be seen 

 presently that there was another green lake, which was the only 

 green one visible in Centeno's time. But, in comparison with the 

 large surface of vivid emerald green water with the yellow margin,, 

 its waters looked quite pale. The two basins of green water, both 

 of large extent, and of such different tints, could not of course 

 have escaped the observation of the Spanish geologist had they 

 existed in his time, but he makes no mention of them. The bright 

 emerald green lake formed a portion of the yellow lake, according 

 to his map. The change of colour, esi>ecially so remarkable a 

 change, is singular and interesting. It may possibly be accounted 

 for by supposing that, as the gaseous emanations had ceased, the 

 sulphurous mud had subsided, and left the natural colour of the 

 water to appear. 



Bluislirgreen Lake Crater. — The colour of this lake was, in 1885, 

 about the same as that of the sea in moderate depths, where the 

 blue colour is not decided. The tints seemed beautiful to the 

 Spanish geologists, but by the side of the brilliant yellow and 

 green tints of the other waters it seemed poor in colour. In 1883, 



