Cellulose in the Light of the X-Rays1

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Abstract

ONE of the most fascinating features that emerge during the closer study of natural constructions is surely the extended use of certain atoms, certain molecules, and certain ways of combining molecules; while other atoms, molcules, and combinations are but seldom employed. Thus, for example, half the world of which we have knowledge, is made of oxygen: silicon is used to the extent of 27 per cent, aluminum 8 per cent, iron and a few others make up most of the remainder, and some eighty or more of the 92 kinds of atoms cannot muster 2 per cent between them. The seas that cover the larger part of the earth's surface give to the water molecule H2O easy precedence over all others. In the rocks, the oxygen atoms govern the structure: the recent work on the silicates by W. L. Bragg and his collaborators shows us that we may regard the great bulk of the earth's crust as a piling together of bulky oxygen atoms cemented by atoms of other kinds such as silicon, aluminium, iron, or magnesium. Sometimes the piling is of the simplest character, and seems to depend for the most part on considerations of space to be occupied. Sometimes, as in quartz, more complicated structures are framed in order to satisfy the directional qualities of the mutual attractions of silicon and oxygen.

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    Discourse delivered at the Royal Institution on Friday, Jan. 24.

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