The Magic Capsules

A humble project to improve carbon copying has spawned a whole family of technical advances and is still reproducing wildly. It may even end by simulating the structure of the human brain.

The take-off point, says Robert G. Chollar, research chief of the National Cash Register Co. at Dayton, was a trick paper coated with clay on one side and with a special colorless ink on the other side. When the sheets were superimposed and written or typed on, the clay and ink were forced into contact. The ink turned deep blue, making a "carbon copy" without carbon, but the paper was no good because in time the ink seeped through it, making unauthorized contact with the clay and staining the paper blue.

But the Cash men were not licked. To keep the ink from joining the clay, they dissolved it in oil and churned it into microscopic droplets in a solution of gelatin and other gummy colloids. Then they caused the gelatin to precipitate on the oil droplets, enclosing them in capsules only one ten-thousandth inch in diameter. This trick solved the problem. The capsules and clay can be on the same side of the paper, but the paper remains white until pressure of a pencil or impact of a typewriter breaks the capsules; then the ink mixes with clay and turns blue.

New Matter. Cash now manufactures capsules by the carload for use in copying paper, but long before the capsules became a commercial success, the research men found more interesting jobs for them to do. In a sense, the microscopic capsules are a new form of matter, with properties of both liquids and solids. The liquid chemicals inside them may be highly reactive, but until the capsules are broken they remain almost as inert as sand.

The Cash men are now building their capsules into dozens of experimental products. They have colorless crayons that make marks only on prepared paper (nice for the kids and the wallpaper). Capsules can be made light-sensitive so that they form a photographic image. They can be magnetized and polarized. Unstable drugs and vitamins can be encapsulated to protect them from air and moisture. Tissue paper impregnated with perfume-filled capsules has no odor until it is rubbed gently on the skin.

Chemical Memory. Some of these applications promise to grow into important businesses, but the Cash research men have long since taken off into wilder blue yonders of capsule science. Most interesting capsules produced so far are filled with a liquid photochromic dye that turns blue when exposed to light of a certain wave length and loses its color when light of another wave length hits it. The Cash men are hard at work building these talented capsules into a "chemical memory" for computing machines. A transparent film impregnated with photochromic capsules can be written upon in coded dots of color by a hair-thin beam of light. A beam of neutral light that does not affect the dots can read them off in thousandths of a second, or a beam of bleaching wave length can erase them. The capsules can be made so small that the entire Bible could be printed in code on a few sheets of film the size of typewriter paper.

The Cash men admire their capsules but they are quick to point out that nature produced them before their company got into the game. The cells that form the bodies of living organisms have the same basic function as Cash's capsules. Their walls enclose droplets of highly reactive protoplasm and separate it from the surrounding medium. The walls of nature's cells are permeable to specific chemicals and to electric currents. The Cash men see no reason why their synthetic cells (which are about the same size) should not be trained to behave in this way too. They are not trying to synthesize bacteria or protozoa, but there is at least a possibility that Cash's capsules can be made to resemble the neurons (nerve cells) of the human brain and to take over some of their functions.

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