454 W. T. BRIGHAM ON THE VOLCANIC PHENOMENA 



that natives have often brought me a carefully treasured fragment believing it gold, and 

 eager to find more. 



Common Salt. 



This mineral is not common in the crater of Kilauea, and there are no traces of it in the 

 tufa cones, with the exception of Aliapaakai where it is deposited in crusts and concretions 

 every dry season, to be redissolved at every freshet. In former times this salt lake furnished 

 a large supply of good salt, but for some years it has been wholly neglected. This is found 

 on the upper walls as well as in the basin. 



Sal ammoniac. 



Generally this salt is much contaminated with iron in Kilauea, where it is found in the 

 caves, and just beneath the crust of the floor of the crater. B. Silliman analyzed a specimen 

 obtained by the United States Exploring Expedition with the following result : — 



N H 4 CI Fe CI Fe 2 3 Al CI Insoluble and loss. 



65.53 12.14 8.10 13.00 1.23 = 100. 



Specimens nearly pure- were obtained in a crevice of a burning cone. 



Hydrochloric Acid. 



Taking Vesuvius as a model, it has been supposed that hydrochloric acid is a usual product 

 of active volcanoes ; it is, however, quite rare in Kilauea, and I cannot find that it has been 

 observed in the eruptions of Mauna Loa. Very little is found even in combination. 



Hcemaiite. 



Although the basaltic lava contains a large proportion of iron, enough to color the result- 

 ing soil bright red, no available deposits of iron ore have been found. A few fragments of 

 haematite were found loose in the beds of streams on Kauai, and near Nuuanu pali on Oahu. 

 They were much worn, and did not exhibit any external crystalline form. Perhaps an 

 altered Limonite. A fine red powder was found on Oahu which makes an excellent pigment. 



Limonite. 



On the edge of the lava flow of 1855 from Mauna L6a, where it passed through a wooded 

 land, rounded masses of this mineral were found from three to twelve inches in diameter 

 and of the consistency of fresh putty, so that they could easily be cut with a knife, or moulded 

 with the finger. On drying, these lumps crumbled and exhibited a fibrous structure. At 

 Kaliiwaa on Oahu, an ochre occurs of a finer texture. Both of these ochres form pigments 

 of considerable body, little grit, and the color of burnt sienna. The impure varieties found 

 near the sulphur banks, have been used in former times as paints, but are now wholly super- 

 seded by the better, imported ochres. It is highly probable that a more careful exploration, 

 on the windward side of Oahu, on Kauai, and possibly in the northern districts of Hawaii, 

 may result in the discovery of small beds of this important ore. 



Sulphurous Acid. 



The cloud of vapor which overhangs the active portion of Kilauea, is mostly sulphurous 

 acid. Boussingault found, in the volcano of Cumbal, hydrosulphuric acid only in the higher 

 and cooler parts, where the temperature of the fissures did not exceed 185° Fahr., while in 



