TRANSACTIOIifS OF SECTION B. 



581 



Three classes of springs -were considered : — 



1. Near Lake Taupo. 



2. lu the famous ' Hot Lake District' of Rotorua and Rotomahana, where are 

 Tinique sihceous terraces. 



3. On White Island, in the Bay of Plenty. 



I. The springs near Lake Taupo are all more or less siliceous, and remarkable 

 for the presence of free iodine. They are medicinally useful. Particulars of ten 

 springs were given, in five of which the silica was one-half of the total solid con- 

 stituents; and in two more, one-third. The maximum here was 28"51 grains 

 silica per gallon ; total solids, 56-47 grains. Two contained respectively 40-5 and 

 56-1 grains chlorine (chiefly as sodium chloride), and 0-714 and 1-012 grains per 

 gallon of free iodine. Another was so strongly charged with sulphates of iron and 

 alumina as to taint a river therewith for seventy miles, its whole course. 



II. Hot Lake District : — 



On the shores of Lake Rotomahana were two wonderfid siliceous terraces, 

 formed by the deposition of silica from two intermittent boiling springs, of the 

 following composition, according to the Colonial Laboratory reports : — • 



White teiTace Pink terrace 



Monosilicate of soda 68-48 ■ 



„ lime 



„ magnesia 



„ iron 



Silica, free 

 Chloride of potassium 



„ sodium . 



Sulphate of lime 

 „ soda 



Alumina (as phosphate) . 

 Iron oxides . . . 



Grains per gallon 



The writer had brought home a spec 

 analysed it, with the annexed result : — 



Water expelled by red heat 9-67 per cent. 



Salts soluble in water, almost entirely sodium silicate . 0-59 „ 



Anhydrous silica 87-35 „ 



Lime, soda, and alumina, by difference, but all detected . 2-39 „ 



10000 

 No chlorine could be discovered in it, though there was so much in the water 

 whence it was derived. It was also quite free from iron. 



Of fifteen springs in this district, live contained sUicate of soda, and twelve free 

 silica. Chloride of sodium was present in eight. Lime-salts only amounted 

 usually to two or three grains per gallon. Free hydrochloric acid was found in 

 eight, always with free silica, and six of these eight contained free sulphuric acid 

 (one as much as 77 grains per gallon). 



III. White Island springs. 



This island is the summit of an extinct volcano, whose crater is occupied by a 

 lake of strong mineral water, fed by intermittent geysers and boiling springs, and 

 containing more than 10,000 grains per gallon of free hydi-ochloric acid. All the 

 springs deposited sulphur and sulphate of lime. Annexed are the analyses : — 



Sulphate of iron 



„ soda 



„ potash . 



„ lime 



„ magnesia 



„ alumina 



„ ammonia 



Carried forward 



144-46 154-13 



men of the siliceous sinter, and carefully 



