The Silver Wand 167
als stopped growth of all the bacteria at both poles, as long as we used
high currents. Unfortunately, high currents also produced toxic ef-
fects—chemical changes in the medium, gas formation, and corrosion—
with all but the silver electrodes. Apparently such currents through
most metals "worked" by poisoning both bacteria and nearby tissues.
Our preliminary observations turned out to be right. Silver at the
positive pole killed or deactivated every type of bacteria without side
effects, even with very low currents. We also tried the silver wires on
bacteria grown in cultures of mouse connective tissue and bone marrow,
and the ions wiped out the bacteria without affecting the living mouse
cells. We were certain it was the silver ions that did the job, rather than
the current, when we found that the silver-impregnated culture medium
killed new bacteria placed in it even after the current was switched off.
The only other metal that had any effect was gold; it worked against
Staphylococcus, but not nearly as well as silver.
Of course, the germ-killing action of silver had been known for some
time. At the turn of the century, silver foil was considered the best
infection-preventive dressing for wounds. Writing in 1913, the eminent
surgeon William Stewart Halsted referred to the centuries-old practice of
putting silver wire in wounds, then said of the foil: "I know of nothing
which could quite take its place, nor have I known any one to abandon
it who had thoroughly familiarized himself with the technic of its em-
ployment."
With the advent of better infection-fighting drugs, silver fell out of
favor, because its ions bind avidly to proteins and thus don't penetrate
tissue beyond the very surface. A few silver compounds still have spe-
cialized uses in some eye, nose, and throat infections, and the Soviets use
silver ions to sterilize recycled water aboard their space stations, but for
the most part medicine has abandoned the metal. Electrified silver offers
several advantages over previous forms, however. There are no other ions
besides silver to burden the tissues. The current "injects" or drives the
silver ions further than simple diffusion can. Moreover, it's especially
well suited for use against several kinds of bacteria simultaneously. It
kills even antibiotic-resistant strains, and also works on fungus infec-
tions.
For treating wounds, however, there was one big problem with the
technique. Its effect was still too local, extending only about a quarter
inch from the wire. For large areas we needed something like a piece of
window screen made of silver, but this would have been expensive and
also too stiff to mold into the contours of a wound.
We'd been doing our clinical experimens with financial support from a