Chapter Pericranial to Periœci of P by Webster's Dictionary (1913 Edition)

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A similar relation had been enunciated in a crude way by Newlands; but the law in its effective form was developed and elaborated by Mendelejeff, whence it is sometimes called Mendelejeff's law. Important extensions of it were also made by L. Meyer. By this means Mendelejeff predicted with remarkable accuracy the hypothetical elements ekaboron, ekaluminium, and ekasilicon, afterwards discovered and named respectively scandium, gallium, and germanium.

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Periodic star (Astron.), a variable star whose changes of brightness recur at fixed periods. — Periodic time of a heavenly body (Astron.), the time of a complete revolution of the body about the sun, or of a satellite about its primary.

Periodical
(Pe`ri*od"ic*al), n. A magazine or other publication which appears at stated or regular intervals.

Periodicalist
(Pe`ri*od"ic*al*ist), n. One who publishes, or writes for, a periodical.

Periodically
(Pe`ri*od"ic*al*ly), adv. In a periodical manner.

Periodicalness
(Pe`ri*od"ic*al*ness), n. Periodicity.

Periodicity
(Pe`ri*o*dic"i*ty) n.; pl. Periodicities [Cf. F. périodicité.] The quality or state of being periodical, or regularly recurrent; as, the periodicity in the vital phenomena of plants. Henfrey.

Periodide
(Per*i"o*dide) n. [Pref. per- + iodide.] An iodide containing a higher proportion of iodine than any other iodide of the same substance or series.

Periodontal
(Per`i*o*don"tal) a. [Pref. peri- + Gr. tooth.] (Anat.) Surrounding the teeth.

Periodoscope
(Pe`ri*od"o*scope) n. [Period + -scope.] (Med.) A table or other means for calculating the periodical functions of women. Dunglison.

Periœci
(||Per`i*œ"ci, Per`i*œ"cians), n. pl. [NL. perioeci, fr. Gr. around + house, dwelling.] Those who live on the same parallel of latitude but on opposite meridians, so that it is noon in one place when it is midnight in the other. Compare Antœci.