LEAD TREES WITH THEIR ROOTS IN THE GROUND HARRIETT H. FILLINGER HoUins College, Hollins, Virginia A FEW years ago it occurred to one of our seniors, Katherine Dilworth, who was working on reactions in silicic acid gels, to try to make a "lead tree" growing right side up instead of hanging suspended by its "roots" from the surface of the? gel. She was quite successful, as have been many subsequent attempts. The accompanying photograph shows three "lead trees" made as an extra, voluntary piece of work by a member of our freshman chemistry class last year. The directions given in Holmes's "Laboratory Manual of Colloid Chemistry" were used and were altered in only one respect. The lump of tin or zinc used to displace the lead ions in the gel was placed in the hottom of the tube and the mixture of silicate solution, lead salt, and acid was poured in on top and allowed to set. The "trees" seem to grow upward nearly as easily as downward and produce beautiful effects which present a more fern-like appearance than when growing suspended from the surface of the gel. In many cases the main branches seem to follow almost a sine curve. As indicated in the photograph, the mass of the metal used to displace the lead ions is hidden, or practically hidden, from view when the tubes are placed in the individual stopper stands recently described
by the author.' This arrangement makes the tubes present a very pleasing appearance in a display cabinet. J. CHEM.EDUC., 11, 554 (&t.. 1934).
