I I'll 



ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably 

 prepared and signed by themselves, are forwarded promptly to the editors. Each 

 of the scientific bureaus in Washington has a representative authorized to for- 

 ward such material to this journal and abstracts of official publications should 

 be transmitted thru the representative of the bureau in which they originate. 

 The abstracts should conform in length and general style to those appearing in 

 this issue. 



GEOLOGY. — Some lavas of Monte Arci, Sardinia. Henry S. Wash- 

 ington. Am. Jour. Sci. (4). 1913. 

 This extinct volcano was visited in October, 1904. It has not been 

 described since 1857. It is shown that the volcano consists of a core 

 of rhyolite, with later flows of dacite, andesite and trachyte, closing; 

 with extensive sheets of basalt, in many respects resembling the nearby 

 and better known Monte Ferru. Detailed petrographic descriptions 

 of the lavas are given, together with seven complete analyses. An 

 apparenth- new mineral was found, which is to be further investigated. 

 The paper is a preliminary one, and the volcano is worthy of another 

 visit and fuller study. H. S. AV. 



GEOLOGY. — Observations on the Daubree experiment and capillarity in 

 relation to certain geological speculations. John Johnston and L. 

 H. Adams. J. Geol. 1913. 

 Those who believe that meteoric waters are an important factor in 

 the production of the phenomena of volcanism must always face the 

 problem of devising a plausible account of the manner in which acces- 

 sions of water can be introduced into the magma. This difficulty they 

 have endeavored to obviate b}^ instancing an experiment of Daubree, 

 who found that water would pass thru a porous sandstone against a cer- 

 tain excess counter pressure of steam. This passage of water is, as 

 Daubree pointed out, a manifestation of capillar}^ action; the authors 

 show that this same effect may be secured by means of a much simpler 

 experimental arrangement. Now capillary forces are effective only 

 when there is a surface of separation within the pores; moreover they 

 diminish steadily with, rise of temperature, and vanish at the critical 



