[ad. med. or mod.L. transpīrātion-em, n. of action from transpīrāre to TRANSPIRE; perh. through F. transpiration (1541 in Hatz.-Darm.).] The action or process of transpiring.
1. Exhalation through the skin or surface of the body; formerly, also, evaporation. Also concr. matter transpired.
1562. Bulleyn, Bulwark, Dial. Soarnes & Chir., 16 b. Expulsed, or auoided by inuisible transpiracion, which is one of the forces, or benefits of nature.
1605. Timme, Quersit., I. xv. 75. Mercury and sulphur doe vanish away by an insensible transpiration.
1707. Curios. in Husb. & Gard., 102. A viscous humour,… a plain Transpiration from the Plant.
1718. Ozell, trans. Tournefort’s Voy. Levant, I. 131. It supples and mollifies the Skin, thereby facilitating Transpiration.
1826. Kirby & Sp., Entomol., IV. xli. 130. The substance secreted appears to be a transpiration through the pores of the body.
1879. G. Gladstone, in Cassell’s Techn. Educ., IV. 204/1. The products of transpiration are always of a more or less oily nature.
1898. P. Manson, Trop. Diseases, xxii. 338. The excessive loss of fluid by cutaneous transpiration creates a powerful thirst.
b. Emanation, effluence. Obs. rare.
1652. J. Wright, trans. Camus’ Nat. Paradox, X. 248. It is probable that by some kinds of transpiration, or by the means of Spirits, things acted at a distance are conveyed to persons absent, and represented to them in their sleep.
1675. Traherne, Chr. Ethics, 74. A mystery … perhaps founded in a grateful transpiration of spirits from one to the other.
c. fig. Outflow (of affection, etc.).
1821–30. Ld. Cockburn, Mem., 268. Always beloved for the constant transpiration of an affectionate and cheerful heart.
2. Bot. The exhalation of watery vapor from the surface of the leaves and other parts of plants, in connection with the passage of water or sap through the tissues.
1551. Turner, Herbal, I. P ij. The floures and leues … whiche … by ventyng out or transpiration maketh rype and digesteth.
1786. T. Jefferson, Writ. (1859), II. 56. These leaves having a power of keeping themselves cool by their own transpiration, they impart no heat to the air by contact.
1878. McNab, Bot., iv. (1883), 99. The water that plants give off as watery vapour by transpiration through the stomata.
attrib. 1895. Oliver, trans. Kerner’s Nat. Hist. Plants, I. 276. The bundles of woody cells and vessels … serve as conductors of the transpiration current. Ibid., 280. The stomata or transpiration-pores which pierce the epidermis of the leaf.
3. Physics. The passage of a gas or liquid under pressure through a capillary tube or porous substance.
1867. Hirst, in Brande & Cox’s Dict. Sc., etc., s.v., The transpiration of a gas is uninfluenced by the material of which a tube is constructed; it increases with pressure—the greater the density, the shorter the time of transpiration.
1870. Atkinson, trans. Ganot’s Physics (ed. 4), § 132. For the same gas, the rate of transpiration increases, other things being equal, directly as the pressure.
4. The action or fact of something transpiring or becoming indirectly known; also, that which transpires (i.e., in quot. [erron.] happens). rare.
1802–12. Bentham, Ration. Judic. Evid. (1827), III. 110. Causes of transpiration … disclosure, with or without treachery, on the part of one or more of the co-delinquents.
1908. Academy, 7 March, 529/2. ‘I there prosecuted my enquiries and observed for myself what transpired.’ The transpirations are disappointing.
