From Ohio History Central
On July 5, 1955, Dayton, Ohio, resident and National Cash Register Company employee Barrett K. Green received a patent for the process of microencapsulation. Microencapsulation involves filling capsules with liquid. Over a period of time and under certain conditions, the capsules break open, dispensing the liquid.
Green first applied his new invention to typing paper. He used microencapsulation to manufacture the first carbon-free carbon paper in the world. When placed between two sheets of paper, carbon paper would create a duplicate copy of words written or typed on one sheet onto the other sheet of paper. With microencapsulation, by placing two sheets of paper together, a writer or typist only had to apply pressure to the paper to duplicate what was written or typed onto the other sheet of paper. No carbon paper was necessary.
Green and the National Cash Register Company eventually applied microencapsulation to other products. Microencapsulation allowed for the creation of scratch-and-sniff advertisements. The first company to utilize scratch-and-sniff technology was the Dayton Power & Light Company. This firm sent cards with scratch-and-sniff technology to allow its customers to distinguish the smell of natural gas.Perhaps the most important contribution of microencapsulation was to the field of pharmacy. Microencapsulation allowed scientists to develop pills that slowly released medication into a patient, allowing the medicine to be dispensed gradually over several hours.