xxm] I RETURN TO ITALY 



other hollows of the eruptive rocks, and also through eruptive action 

 be eventually injected, as it were, into the hollows of the limestone 

 formations. If all this be admitted, and the presence in the neigh- 

 bourhood of the caves of cinnabar, i.e. sulphide of mercury, be 

 taken into account, 1 it is easy to understand how gold may be found 

 in caves. My explanation is the following : — The heat due to vol- 

 canic action reduced the cinnabar, freeing metallic mercury. This, in 

 contact with particles of gold, would at once amalgamate with them, 

 carrying them off to where its fluid condition and weight allowed it 

 to rest, namely in the fissures of caves. Any further evolution 

 of heat would volatilise the mercury and leave the gold as it is found, 

 i.e. in more or less dendritic masses of varying but always small 

 dimensions, adhering to the limestone rock on the sides or in the 

 hollows of caves. Or, again, the action of carbonic water dissolving 

 portions of the limestone rocks may have further contributed to- 

 wards fixing the particles of liberated gold in their mass. Amongst 

 the specimens I collected, which were afterwards lost, was a fine 

 and most interesting one, showing native gold in the fragment 

 of the limestone rock. 



The cave of Paku, which I went to see, was very difficult to get 

 at. In addition to gold, edible nests of Collocalia nidifwa were to 

 be got there. The wooden props and steps by which access to the 

 cave was rendered possible, were, however, in a rotten condition 

 and quite useless, so I had to give up my attempt to explore its 

 recesses. I was told that some time before a large quantity of 

 human bones, especially skulls, had been found in this cave, and 

 that they had been broken up by the Dyaks. In another cave, 

 too, not far from that of Paku, bones had been found, but very 

 friable, and reduced to semi-fossilised fragments. The lime- 

 stone of these caves is sometimes white, sometimes dark in colour, 

 crossed with veins of flint or chert, and often containing fossils, 

 which are conspicuously visible. 



This was my last excursion in Borneo. Before returning to 

 Europe I had intended paying a visit to Java, starting from Ponti- 

 anak, whither I had decided to go overland from Kuching. Every- 

 thing was ready for my departure on the 20th January, 1868, 

 when a violent attack of fever completely prostrated me. Mean- 

 while the mail steamer arrived, and as I had lost all hope of regaining 

 sufficient strength to undertake a fatiguing journey overland, I 

 decided to give it up, and took my passage on the steamer to Singa- 

 pore, the first step on my journey homeward bound. 



1 A cinnabar mine in that district was worked with profit by the Borneo 

 Company. 



353 A A 



