Evening star., 1952-12-26
Bouncing Protons Used
To Detect Impurities
Reveal Minute Mutter
On Surface of Material
By Thomos R. Henry

ny lhomoS K. Henry
Detection of a hundred -billionth of
gram, or about ree-trillionth of an
ounce, of any of the elements on the
surface of material is possible with a
five-ton instrument in use at the STAN
ford Research Institute.
This proton bombarder now is being
used on several investigations for Army
Ordnance. which is greatly concerned
with the presence of any impurities on
the surfaces of metals. 1t has just been
described to the American Association
for the Advancement of Science here
by DR.. William c. Estler of the Stanford
faculty
Protons. infinitesimally minute non-
electrical elementary PARTICLES are fired
against the surface of the material
under consideration. They hit the
atoms of the surface and bounce back
like rubber balls. After all, an atom
is pretty big compared to a proton.
The speed with which they bounce de-
pends on the size of the atoms they hit.
They bounce between two powerful elec-
tromagnets. These defect them pre-
cisely according to the speed Of the
rebound. which can be determined for
each of the known elements.
Light Indicates Impurities.
The bouncing protons finally hit a
phosphorescent screen which emits
pulses of light as it is struck. The result.
DR.. Estler says, can be compared to the
rainbow-like spectrum which results
when light passes through a crystal Of
some sort. The point at which the
magnet-deflected bouncing balls hit the
screen indicates what kinds of atoms
were hit.
The Stanford workers are not con-
cerned, of course, with what material
forms the major part of the surface
iron, for example. This is known before
they start work. So, in practice. the
protons bouncing from iron would be
shut off and only those which have hit
atoms of stuff which probably shouldn't
be there are recorded in the spectrum.
Within its limits this probably is the
most precise instrument for chemical
analysis ever devised. Unfortunately.
the protons will not penetrate below the
surface, or wouldn't bounce very we'll if
they did. In some cases, however, it is
found that the chemical pecularities
found at the surface extend through
the material.
Grating of Grasses Possible.
Grating of grasses, supposed bo-
>tanical impossibility, has just been de-
scribed for the first time.
Crafts of bamboo, sugar cane and
guinea grass, the later a common forage
grass in the South, are reported to the
American Association for the Advance
ment of Science here by DR.. Thomas j..
Muzik of the Federal Agricultural Ex-
pertinent Station at Mayaguez, Puerto
Rico, and Carl d. LaRue of the Uni
versity of Michigan.
The possibility of grating, 1t has been
presumed, has been confined to woody
plants, and the art plays a notable part
in the orchard and Towering shrub in
dustry. There have been occasional
claims of successful CRAFTS of grasses for
the past 100 years but these have been
given little credence.
In woody plants the procedure has
been relatively simple. An embryonic
layer of plant cells present in the stems
simply is fastened against similar en-
bryonic layer of the plant on which the
graft is made.
This so-called meristem exists only in
very primitive form in the grass family.
Skill and Care Necessary.
The new technique by which grass
CRAFTS are successful, DR.. Muzik reports
to the American Association, requires
considerable skill and care. The shoot
must be grasped firmly and broken with
a quick jerk. 1t breaks along weak
line of cells at least comparable to the
meristem. The fit between the two
stems with which the graft is made
must be precise.
Such gratis, DR.. Muzik says, succeed
in about per cent of cases tried.
Until this take" can be improved, he
says, the process will have no CONNER
cial Importance, but it may lead to
a better understanding of plant growth.
After a successful graft begins to
grow, it sometimes continues at about
the same rate as for intact plants. In
other cases, however, the growth rate
is very slow. One bamboo graft grew
approximately 10 feet in eight months
while another, made by precisely the
same technique, remained green but
hardly grew at all during that period.