PRIMARY a.
r rocks supposed to have been first formed, being crystalline and containing no organic remains, as granite, gneiss, etc.; -- called also primitive rocks. The terms Secondary, Tertiary, and Quaternary rocks have also been used in like manner, but of these the last two only are now in use. -- Primary salt (Chem.), a sa…
RECIPROCAL a.
als for given quantities. See the Phrases below. Reciprocal equation (Math.), one which remains unchanged in form when the reciprocal of the unknown quantity is substituted for that quantity. -- Reciprocal figures (Geom.), two figures of the same kind (as triangles, parallelograms, prisms, etc.), so related that two s…