218 REACTION OF THE INTERIOR OF THE EARTH 



and by London, with the fabulous stories of the Upas or 

 poison-tree. The most remarkable of these, situated in 

 the mountains of Dieng, near Batur, has been scientifically 

 described by Junghuhn; it is called Pakaraman,the Island 

 Valley of Death. It is a fallen-in, funnel-shaped hol- 

 low, situated on the side of a mountain, in which the 

 height of the unrespirable stratum of carbonic acid gas 

 varies very much at different seasons. Skeletons of 

 wild swine, tigers, and birds are often found there. ( 30 ) 

 The poison-tree, pohon or piihn, the upas of the Malays 

 (the Antaris toxicaria of the traveller Leschenault de la 

 Tour), and its harmless exhalations, have nothing what- 

 soever to do with these fatal effects. C 301 ) 



I will conclude this section on salses and on gas and 

 vapour springs with a description of a case which may 

 be interesting to geologists on account of the kind of 

 rock from which hot sulphureous vapours are developed. 

 When making the delightful, but somewhat arduous, 

 passage across the central Cordillera of Quindiu, from 

 the valley of the Rio Magdalena to the Cauca valley (it 

 took me 14 or 15 days' foot travelling, sleeping always 

 in the open air, to pass over the crest, 11,497 feet above 

 the sea), I visited the Azufral, situated, at a height of 

 6810 feet, on the west of the station of El Moral. In a 

 rather dark-coloured mica-slate, which is superposed 

 on a garnet-bearing gneiss, and, together with it, sur- 

 rounds the high granite cupolas of La Ceja and La 

 Garita del Paramo, I saw in the narrow valley (Que- 

 brada del Azufral) warm sulphureous vapours issue 

 from the clefts in the rock. As the vapours are mixed 

 with sulphuretted hydrogen and much carbonic acid gas, 

 a stupefying sensation of giddiness, felt on stooping down 



