328 W. S. Bayley — Fulgurite from Waterville, Me. 



respectively. Its exterior surface is very rough and is thickly 

 covered with sand grains, while its interior is glazed with 

 a transparent coating of light yellowish green glass about 

 a millimeter in thickness. This glass with its adhering sand 

 grains compose the tube. A very close inspection of the glass 

 discloses the presence in it of tiny whitish enamel-like portions, 

 that probably mark the positions of some refractory particles 

 that were not completely fused, and the existence of numerous 

 small pores that may represent the original spaces between the 

 grains. 



The corrugations noted by Mr. Merrill* in the fulgurites 

 from Whitesides Co., 111., are very noticeable in the Waterville 

 specimen, but instead of running longitudinally, as in the first 

 case, they possess a slightly spiral twist in opposite directions 

 on opposite sides of the tube. These corrugations or " wings " 

 are covered with little knobs, that are hollow spaces enclosed 

 within walls of glass and sand. Only in these knobs, however, 

 are the ridges hollow. Throughout their greater extent the 

 " wings " are merely a single layer of glass to both sides of 

 which sand grains adhere in large numbers. The continuity 

 of the glass across the corrugations seems to lend credence to 

 the view of Merrill, that these irregu- 

 larities on the surfaces of sand-fulgu- 

 rites are due, not to the collapsing of 

 the walls of the tube, as suggested by 

 Wichmann, but to the selective power 

 of the electricity in directing its course 

 through the sand. That the corruga- 

 tions are original structures, due to the 

 action of the electric current, rather 

 than accidental ones, is also indicated 

 by their spiral twist (see figure). 



Unfortunately insufficient material 

 forbade analyses of the various por- 

 tions of the tube, and its fragility 

 would not admit of thin sections being 

 cut from it, so a small fragment was 

 crumbled between the fingers, and the 

 resulting particles were examined un- 

 der the microscope. The glass could 

 easily be distinguished from the grains 

 of sand. Some of the glass fragments 

 were perfectly colorless, others were 

 greenish, and all were filled with little 

 air bubbles. JSo microlites of any 

 kind were seen in them, but occasionally a small unfused sand 

 grain could be detected imbedded in a perfectly isotropic 

 matrix. 



* Proc. U. S. Nat. Mus. for 1886, p. 85. 



