1894.] NATURAL SCIENCES OF PHILADELPHIA. 105 



VOLCANIC PEODUCTS FROM THE HAWAIIAN ISLANDS. 

 BY E. GOLDSMITH. 



Kauaiite. — As the Hawaiian Islands are known to be of volcanic 

 origin, the appearance in a crater of a substance resembling chalk 

 may occasion surprise. 



Professors Benj. Sharp and W. Libbey, Jr. who visited a number 

 of the Pacific Islands during the past year, secured, on the Island of 

 Kauai, a specimen which, in external appearance, very much re- 

 sembles chalk. Although definite infi)rmation as to its relation to 

 adjacent solfataras and cracks is desirable it has not been obtained, 

 nor is it known whether the material is rare or abundant. 



The specimen weighed but a few ounces. To the eye it appears 

 to be amorphous and made up of an extremely fine powder which 

 soils the fingers when touched. Despite its softness the particles ad- 

 here firmly, its hardness being about 0.5. It can be easily cut 

 with a knife into any shape, precisely like chalk. It is perfectly 

 dull to the reflected ray of light ; the color is nearly white or, to be 

 exact, of a faint cream tint. One side of the specimen is covered 

 with a thin coating of brown oxide of iron. The streak is white and 

 its lines on a black-board cannot be distinguished from lines made 

 with white chalk. Only formless granules are revealed under the 

 microscope and, strange to say, increasing power serves but to show 

 more of the granules in the field without any increase in size. In 

 all of the granules the diameters seem to be about the same. 



If the material be iml^edded in balsam and interposed between the 

 crossed Nicol prisms, light is transmitted. The ray of light trans- 

 mitted under these conditions is pale blue and no other color of 

 polarization is produced. By this means the particles can be ob- 

 served to the best advantage, as, when projected on a dark back- 

 ground, singly and in groups, the contrast favors observation. In the 

 manner that the modern chemist describes the molecule do these fine 

 particles fi)rm groups and the picture presented in the field 

 of view so strikingly resembles the molecular conception of the 

 present day as to almost tempt one to believe that the atom had at 

 last become visible, provided we assumed that the fine particles 

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