766 



SCIENCE 



[N. S. Vol. XXVII. No. ( 



strand plants to the environment, as shown 

 by a histological study of the leaves. The 

 epidermal structures developed in the 

 leaves to prevent transpiration and desic- 

 cation, brought about by the intense light 

 and heat of the sun and the reflection of 

 the white sand, are described and illus- 

 trated. Thickening of the cuticle, the de- 

 velopment of Avater-storage tissue, and a 

 hairy covering and the depression of the 

 stomata are the principal changes brought 

 about by the exterior conditions. 



The Explosion of the Saratoga Septic 

 Tank: William Pitt Mason, of Troy, 

 N. T. 



The explosion of a tank used for the 

 storage of sewage, and supposed to be due 

 to the ignition of an explosive mixture of 

 marsh gas and air, is discussed. The 

 marsh gas is derived from the fermenta- 

 tion of the sewage, and the ignition is 

 assigned to the generation of phosphine, 

 which is supposed to have ignited spon- 

 taneously. 



Some Chilean Copper Minerals: Harry F. 



Keller, of Philadelphia. 



The author describes a number of raw 

 minerals containing copper, from the mines 

 in the Province of Tarapaea, Chile. Among 

 these, the most interesting are peloeonite, 

 a manganese ore containing a consider- 

 able proportion of copper; a new double 

 sulphate of copper and magnesium, iso- 

 morphous with chalcanthite ; and a beau- 

 tifully crystallized sulphate and arsenate 

 of copper, which could not be identified 

 with any known species. TlTe author ex- 

 pects to follow this communication with 

 others on minerals from Copaquira, Hui- 

 guintipa and other Chilean localities. 



Absorption Spectra of Solutions: H. C. 



Jones, of Johns Hopkins University. 



The object of the present investigation 

 was to ascertain whether combination be- 

 tween the solvent and dissolved substances 



had any effect upon its power to absorb 

 light. Certain salts in the anhydrous state 

 have very different absorption than when 

 combined with water. A solution of an- 

 hydrous neodymium chloride in absolute 

 alcohol gives absorption bands differing 

 from those obtained when a few per cent, 

 of water is added. The application of 

 this observation to the author's theory of 

 hydration is discussed. 



Effect of an Angle in a Wire Conductor 

 on Spark Discharge: Francis E. Niphee,, 

 of St. Louis. 



The problem to be solved is to determine 

 the real current direction in a wire, 

 through which a spark discharge is pass- 

 ing. The spark discharge was that of a 

 long eight-plate machine. One terminal 

 was grounded on a water pipe, the other 

 was grounded in the air. A small wire 

 bent at a sharp right angle was placed 

 vertically in the lines of the earth's mag- 

 netic field, and so connected that the nega- 

 tive discharge could be sent either up or 

 down around the angle and its effect re- 

 corded on a photographic plate placed 

 under the angle. Very interesting photo- 

 graphic results were obtained, but the 

 author does not consider that the main 

 question was conclusively answered. The 

 work is to be continued, using a platinum 

 wire of .002 inch diameter. The electrom- 

 eter will probably be a means for examin- 

 ing the two sides of the angle, and it can be 

 used with a continuous current running 

 through the fine platinum wire. 



Some Results of the Ocean Magnetic Work 

 of the Carnegie Institution of Washing- 

 ton: L. A. Bauer, of Washington. 

 Dr. Bauer described the work of the 

 Galilee expedition in the Pacific since Au- 

 gust, 1905. The work accomplished, 

 briefly stated, is as follows: (a) magnetic 

 observations have been made on the ocean 

 areas which closely approach land observa- 



