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reaclioji of the hkickciiiiiii of silver coins. Tiie vjiiiisliiiig of FI.S, 

 uppareiillv less by escaping tlian l)v cliaiige into H.^SO^ lias already 

 i)een observed by Hkrinoa ^}. 



As far as I he determinations go, llie ^vafer may be taken lo be 

 mineralized only by the ordinary process i. e. lixi\iation of ruck by 

 newly formed sulphui'ic acid. Most likely this wonld be more obvious 

 if the investigahjr had also determined iron and especially natrium, 

 instead of rather strangely restricting himself lo kalium, the absence 

 of which is striking but for the i-est not so a-lonisliing, as we have 

 to do here chiefly with plagioklastic rock. 



Without proper analysis it is impossible lo enter into a discussion 

 of the ({uestions connected with tlit' chemical composition of the 

 solfalare-material ; however unwillingly I must restrict myself to hint 

 at them only to indicate that they are not devoid of interest. Thus 

 the composition of the mud might be of use for the solution of the 

 (piestioii to which phase of \"olcaiiism the formation of the solfatare 

 corresponds, to the basic So|)oetan-eruptions, or — as after-elfect — 

 to the Rindengau-Scmpoe-activity with its more acid products. The 

 high amount of silicious acid if ii'i-efulalile and oi-iginal might ha\e 

 led us lo look foi- some co-i'clatioii with the dacile found by Rinnf, -j 

 near the Walclang, and so possibly lo the unxeiling of an eruplixe 

 phase of still more acid material and presumably higher auti([uity. 

 Confirmation of the supposition just ventured about the miuei-alizalion 

 of the water might on the contrary be an indication that we ha\e 

 to take the solfatare only as the result of the contact of iiililtraliug 

 atmos[)herical watei' wiih hot masses containing sulphides, a pheno- 

 menon of oidy [tartial \olcanic nattii-e. This conclusion would be 

 supported by the circumstance that many of the stones ejected with 

 the mud are rich in pyrites. 



In .March 1910 the mud-field around the s|)ring extended oxer an 

 area, the length of which I estimated at more than 250 M. in the 

 direction along the Pentoe upwards. Downwards the coating of mud 

 did not reach so far, hardly one hundred meters; on the right bniik 

 of the Pentoe whei-e the Ketengen-Rindengan-wall hindered the 

 extension sideways, it was however likewise restricted in the upward 



') JoD Heiiin(.;.\: "Onderzoek van eenijie bronnen en inodderwellen in de Minalias^sa." 

 Nat. Tijdschr. v. N. -Indie Dl. LIV p. 93 et seq. So his opinion that the smell of 

 sulphuretted hydrogen might be locally peculiar to the atmosphere only, and the 

 water itself would be free from it, is not valid for our case. 



~) Prof. Dr. f'^. Rin^e: Beitrag zur Petrographie der Minahassa in Nord Celebes. 

 Silz. Berichte der K. Preussischen Akademie der Wissenschafte, Phys.-Math. Glasse, 

 1900 XXIV p. 482/488. 



