Microcapsules

In the late 1930s Barry Green, a research chemist at the National Cash Register Company in Dayton, began investigating how the concept of microencapsulation might have potential application in copying documents. If specks of dye could be covered with a special fusible coating, forming a microcapsule, the use of ink could prove much less messy and more efficient. Scientists had long been intrigued by the possibilities of controlling the release of an active ingredient by encapsulating it.