Friedlaendeb. — On Neiu Zealand Volcanoes. 603 



proper it kept on steaming furiously, though with slowly 

 decreasing power. This I observed on one occasion, and I 

 was told that it was generally or always the case. 



I had no time to make a petrographic study of Tongariro, 

 and my few specimens are not yet analysed. I know, also, 

 that rather basic rocks have been found in the Tongariro 

 system. Tongariro, however, if compared with Vesuvius or 

 Etna, probably is, as well as Volcano, far more acidic, whereas 

 the Hawaiian volcanoes are known to be ultra-basic. It is 

 therefore perhaps worth mentioning that the character of the 

 activity of these volcanoes to a large extent forms a similar 

 series, as does their chemical composition. We find, in fact, 

 in Hawaii enormous masses of very liquid and almost white- 

 hot ultra-basic lava, and only a very slight amount of steam. 

 We find the reverse in Te Mari and Volcano — very powerful 

 explosive-like eruptions of steam and ashes, whereas the 

 presence of magma betrays itself only occasionally. In fact, 

 any one who did not happen to witness one of these par- 

 oxysms at night-time might doubt the presence of red-hot 

 magma altogether. The colour of the glare, moreover, showed 

 a vivid red heat only ; and the rather angular shape of the 

 erupted rocks denoted a very imperfect fusion, if any. Also, 

 the structure of the very cones — the appearance and steepness 

 of the old lava-currents of Ngauruhoe — shows that the lava 

 must have been viscous. Vesuvius and Etna, which, chemi- 

 cally, are between Hawaii on one side and Tongariro and 

 Volcano (Lipari) on the other side, are also, in their dynamic 

 behaviour, intermediate. Their lava-currents, which I ob- 

 served frequently, as well as those of Hawaii, are less liquid, 

 and apparently also less hot, than those of the Hawaiian 

 volcanoes; but the lava, besides the steam, plays a very 

 important part in their activity. A great display of high- 

 pressure steam and comparatively little lava, therefore, seems 

 to be a characteristic of the more acidic volcano, whilst the 

 opposite feature is a characteristic of the more basic one. 

 This apparent rule, however, needs confirmation by further 

 comparison. 



In another respect Te Mari's activity is interesting ; it 

 shows that the appearance of molten, or at least incandescent, 

 rock — viz., a shower of red-hot projectiles and a glare in the 

 lower parts of the ascending steam — sometimes lasts a very 

 short time only. After a personal inspection of Tarawera and 

 Euawahia I never doubted but that there had been molten 

 rock, but no lava-stream proper; and after my experience with 

 Te Mari I am, if it were possible, more certain still. It has 

 been questioned by persons who visited Tarawera after the 

 main explosion was over — viz., after the morning of the 10th 

 June, 1886 — if there had been any incandescent rock, and 



