410 DOMAIN XII. VOLCANIC. 



forming a coating of two lines in thickness, on 

 which are small grains of a similar nature*. 



" Found in the fissures of the w. s. w. cur- 

 rent of lava. 



" No. XXIII. Deliquescent sea-salt with a 

 martial basis, which flows from those light drosses 

 which are of a reddish yellow colour. 



" From the same fissures. 



" No. XXIV. Martial vitriol adhering to 

 many of the preceding drosses, now of a lively 

 red, now of a greenish yellow, and now of other 

 colours: these drosses remain yet partially co- 

 vered with the selenite of No. XXII. 



" From the same spots as the last : in the 

 eruption of this w. s. \v. current it was very 

 abundant. 



" No. XXV. Martial sal ammoniac, subli- 

 mated in very thin needles, two or three lines in 

 length, and adherent to a light cellular lava of a 

 reddish yellow colour: on examining these 

 needles with a microscope, small articulations 

 are clearly distinguished, composed of octaedra, 

 placed one on the other. 



* " These incrustations of selenite are found in very great abun- 

 dance in the two new currents of lava ; they evince the prompt 

 activity and powerful effect of the sulphuric acid on the calcareous 

 molecules of lava, especially when assisted by heat," 



