Gaffield.] 356 [March 8, 



sizes from less than three fourths of an inch up to three 

 inches in length ; there were about five large females, all in 

 the embrace of males. Say states that his specimens were 

 all found on trees, but no trees were growing near the spot 

 where the last family was found. 



March 3, 1869. 



Vice President, Dr. C. T. Jackson, in the chair. Thirty- 

 seven members present. 



Mr. Thomas Gaffield exhibited some cracked specimens of 

 cruet stoppers, the cavities of which were filled with a con- 

 siderable quantity of water. 



Mr. Gaffield remarked that on the morning of Sunday, the 6th of 



September, a fire occurred in the glass-cutting establishment of J. M. 



• Cook, in Congress St. On Monday morning he visited the ruins of 



tlie fire to search for any sj^ecimens exhibiting the devitrification of 



glass exposed to great and long continued heat. 



He found nothing of this kind, but instead, in a pile of melted 

 glass and cinders of wood, discovered some stopples of glass bottles, 

 cracked on the outside and containing water. These stopples were 

 originally made with a cavity containing a partial vacuum, as the 

 air must have been enclosed when hot, and when cooled must have 

 contracted and filled less space than previously. 



Mr. Gaflield presumed that when the glass stopples were heated red 

 hot by the fire around them, the stream of water from the engines 

 coming in contact with them produced the cracks through which the 

 water rushed in, In sufficient quantity to fill the partial vacuum. 

 The glass was cooled by the water within, and the fire extinguished 

 by the water without, and so the glass contracting to its original size 

 has virtually almost hermetically sealed the imprisoned water. Mr. 

 Gaffield thought that these specimens might throw some light upon 

 the occurrence of crystals with cavities containing liquids, and of 

 mineral geodes lined with ciystals. 



