TITLES AND ABSTRACTS OF PAPERS 161 



PHEXOL RED IXDICATOR AS A\ AID TO THE GEOLOGIST 

 BY EDGAR T. WHERRY 



(Abstract) 



Phenol red is a hrilliaiit indicator, nsed in tlie eheniical laboratory for test- 

 injj reaction. It is yellow when acid, orange-yellow at the neutral point, and 

 violet-red when alkaline : solutions of calcium bicarbonate, and even of calcium 

 carl)onate, in-oduce the alkaline color. It can be carried into the field in dry 

 form and dissolved in water as needed, and may prove useful to the geologist 

 in the following ways: Demonstrating that a given natural v^^ater is "hard" 

 or "soft," the former condition reacting alkaline, the latter acid, toward the 

 indicator : this may enable the source of waters to be determined and help in 

 tracing contacts, fault-lines, etcetera. Ascertaining whether a given rock is 

 calcareous or not, a little rock powder is scraped oft" with a knife or rock 

 fragment and shaken in water, when, if the rock is calcareous, enough will 

 dissolve to affect the indicator and produce the alkaline color. 



Presented with illustrative experiment. 



THE TERNARY SYSTEM Fe^O^ — SO^ — H^O 

 BY H. E. MERWIN AND E. POSNJAK 



{Ahstiact) 



TTie formation of hematite, of the hydrated ferric oxides, of several ferric 

 sulphates which occur as minerals, and of other precipitates not definitely 

 crystalline, and variable in composition like certain natural materials, are 

 considered. 



Presented by the senior author without manuscript, with lantern-slide 

 illustrations. 



BEARING OF EXPERIMENTAL CHEMICAL DATA ON THE FORMATION OF 



SMITHSONITE 



BY THOMAS L. WATSON 



{Ahfitract) 



Smithsonite. which c()rres])onds to the normal carbonate of zinc and is one 

 of several oxidized ores of the metal, is an imi)ortant ore mineral in zinc 

 deposits of certain localities, both in this country and abroad. The mineral 

 is most abundant in limestones and dolomites and their residual decayed 

 products. It is usually associated with other oxidized ores of zinc and some 

 other metals, especially iron and lead, and to some extent copper and silver. 

 Smithsonite is a secondary mineral, regarded at present as having formed in 

 the zone of oxidation by descending waters acting on the corresponding sul- 

 ])bi<le. sphalerite. 



XI— BtT.T.. Oeoi,. Sor. Am.. Vol. ?A, 1010 



