An account is given of the main principles and problems encountered by the device manufacturer in the utilization of semiconductor-grade silicon. The general types of reaction described are illustrated by an account of their application in some research done on the production of silicon in bars 1/2 in diameter, and 2 ft long. The chemical route involved is the reduction of silicon tetrachloride with hydrogen. The properties of the product obtained are described.The major importance of producing silicon in bar form suitable for zone refining, using the floating-zone technique, is described in its relation to the question of crucible contamination factors applying to conventional silicon single-crystal techniques. The development of a simplified form of floating-zone refining apparatus is described, together with experience gained in producing single crystals in the apparatus using various forms of bar silicon, including that produced in a bar silicon plant.In conclusion, an outline is given of some views held on the evaluation of silicon raw material. The main theme is that the most satisfactory trial at present is the production of single crystals in a standard manner and the conduction of observations of resistivity lifetime, conductivity type and high-voltage rectifier yield obtained in a ‘diffusion’ rectifier manufacturing line.