96 



cox. 



Science, show that the water in the crater lakes contained large amounts 

 of easily hj'drolyzed salts, those of aluminium and iron predominated, 

 and that these were in equilibrium with free acid varjdng from 1.28 to 

 2.08 normal. Calculated as hydrochloric acid, the above numbers are 

 equivalent to 4:.65 and 7.57 per cent respectively, and as sulphuric acid 

 the equivalents are 6.14 and 10.38 per cent respectively. All of these 

 lakes disappeared at the time of the eruption. In either event the free 

 acid would in turn react with the other compounds in the mud to form 

 harmless salts of the acids which are shown by analysis to be present, 

 but probably not until injury to the vegetation had taken place. 



I have made a number of analyses of the deposits covering the walls 

 of the crater lakes and have always found them to consist largely of 

 salts of the rock forming metals with no free acids, which shows that 

 the acid in the water thrown on the rocks as spray from the boiling 

 lakes reacts with the rocks themselves. Therefore, one would not expect 

 to find free acid by a chemical analysis, even though it was known to 

 exist in the recent ejecta from the volcano. 



A sample of water taken since the eruption from near the mouth of 

 the north stream flowing into the crater gives corroborative data and 

 indicates that another acid lake is being formed. Its analysis, together 

 with that of water from the larger lake surrounding the volcano, is 

 given in Table III. 



Table III. — Water analyses. 

 [Figures Indicate parts per million.] 



Constituent. 



Color 



Acidity 



Silica (SiOj) 



Iron (Fe) 



Aluminium (Al) 



Manganese (Mn) 



Calcium (Ca) 



Magnesium (Mg) 



Potassium (K) 



Sodium (Na) ' 



Lithium (Li) 



Sulphuric ions (SO4) 



Phosphoric ions (PO4) . 

 Metabolic ions (BOj) - 



Arsenic ions (ASO4) 



Chlorine (01) 



Bromine (Br) 



Iodine (I) 



Water 

 flowing 

 into the 

 new cra- 

 ter lake. » 



Milky. 



. 0069 N. 



710.8 



172.0 



26.1 



79.9 



556.8 



909.3 



237.4 



2, 584. 3 



None. 



2, 732. 



None. 



Small. 



Small. 



6, 024. 3 



Trace. 



None. 



Lake 

 Bombon.*' 



31.5 

 4.2 



53.4 

 49.4 



456.3 

 191.3 



720 



* Temperature 70°. If the stream of which this is a sample has any connection with 

 Lake Bombon, the water dissolves so many and such quantities of salts in passing through 

 the crater wall as no longer to be recognizable. Analyzed by V. Q. Gana. 



i> Analyzed by F. A. Thanisch (1905). 



