234 



SCIENCE. 



[N. S. Vol. XV. No. 371. 



is incorporated with clay, with, the bases of 

 which it for the most part combines. With 

 this powder goes another consisting of a por- 

 ous substance saturated with sulfuric acid. A 

 small quantity of each powder is scattered 

 over the manure pile and by the action of the 

 sulfuric acid on the fluosilicates fluosilicic 

 acid is generated which acts as an antiseptic. 

 In describing this process in the Chemiher 

 Zeitung C. Elschner suggests that it would 

 be more economical to absorb the gases di- 

 rectly by lime and then dry the calcium fluo- 

 silicate formed, and that a powdered bisulfate 

 could be more advantageously used than sul- 

 furic acid. Should some practicable method 

 be devised for iitilizing these noxious gases it 

 would give great value to many apatite de- 

 posits which contain too much fluorspar to be 

 utilized at present. 



A GYPSUM WEATHER-SCALE. 



Aeound the 'Stone Gallery' at the base of 

 St. Paul's Cathedral is a balustrade of Port- 

 land stone, surmounted by a heavy coping of 

 the same material. All of the stone is greatly 

 weathered and coated with a gray or black de- 

 posit, much resembling boiler scale. Under 

 the coping this attains a thickness of three- 

 quarters of an inch. An examination of this 

 deposit is given by E. G. Clayton in the Pro- 

 ceedings of the Chemical Society. It contains 

 no fungoid matter, and contrary to expecta- 

 tion no carbonates were found in it. It is es- 

 sentially calcium sulfate, with a small amount 

 of silica. Since there is no neighboring 

 source of sulfates the conclusion is reached 

 that it has been formed by two centuries' sol- 

 vent and weathering action of rain, charged 

 with sulfurous and sulfuric acids derived 

 from the gases and smoke of innumerable sur- 

 rounding chimneys. The rain water, running 

 and dripping from the under side of the cop- 

 ing stone, has here left an especially thick 

 deposit, which presents a curiously close re- 

 semblance to a deposit of calcareous tufa. 



J. L. H. 



CURRENT NOTES ON PHYSIOGRAPHY. 



PHYSIOGRAPHY OF WISCONSIN. 



Collie has contributed two articles on the 

 physiography of his State. The first ('Physi- 



ography of Wisconsin,' Bull. Amer. Bureau 

 Geogr., II., 1900, 270-287) is a general and 

 elementary account, giving fuller statement 

 of features due to glacial action than to those 

 determined by the underlying rock. The sec- 

 ond ('Wisconsin shore of Lake Superior,' Bull. 

 Geol. Soc. Amer., XII., 1901, 197-216) is the 

 result of detailed local study, with special 

 reference to shore features in the neighbor- 

 hood of the Apostle Islands. These islands 

 consist of horizontal sandstones, usually 

 cliffed and caved along the waterline, but also 

 modified by bars and spits, of which the 

 largest encloses Chequamegon bay. 



In both these papers the bluff by which 

 descent is made from the northwest border of 

 the uplands of disturbed Keweenawan rocks 

 to the lower land of horizontal sandstones 

 bordering Lake Superior is described as a 

 fault scarp, 'formed by the movement of rocks 

 one upon the other, * * * particularly notice- 

 able because it is not formed, as most of the 

 Wisconsin cliffs are, by erosion.' This inter- 

 pretation of the recency of the fault is novel. 

 The considerable erosion indicated by the 

 truncation of the upturned edges of the sand- 

 stones near the fault line throws some doubt 

 upon the accuracy of Collie's view; should it 

 be proved correct the scarp would be an in- 

 teresting addition to our physiographic types, 

 for faults that are young enough to preserve 

 something of their initial topographic expres- 

 sion are rare in the eastern half of our country. 



GLACIAL EROSIOJT IN SKYE. 



The laccolithic mass of the Island of Skye, 

 west of Scotland, was deeply dissected in pre- 

 glacial time. During the glacial period, its 

 mountains bore local glaciers, whose eastern 

 members steimned the great ice sheet that 

 came westward from the Scotch highlands, 

 dividing it into two parts which flowed north- 

 west and southwest out to sea. The effects of 

 the Skye glaciers as agents of erosion have 

 lately been studied by Harker ('Ice Erosion 

 in the Cuillin Hills, Skye,' Trans. Boy. Soc. 

 Edinhurgh, XL., 1901, 221-252, map). He 

 finds that the floors and walls of the ice- 

 scoured valleys exhibit much less relation to 

 rock structure than is usual in districts of 



