970 THE AMERICAN NATURALIST. 
to escape beneath the flange. For permanent sealing, glycer- 
ine is useless with alcohol, and most available oils * creep " so 
rapidly that the groove is soon emptied. However, a heavy 
paraffin oil, obtainable from the Edison Manufacturing Com- 
pany.of New York City, being free from this characteristic, 
and non-volatile, makes an excellent sealing medium. 
WEST VIRGINIA UNIVERSITY, MORGANTOWN, 
October 4, 1900. 
