40S
Raising Water by the Elasticity of Steam,from Porta. [Book [V.
That the same laborious experimenters were acquainted with the proper-ty of steam to displace liquids from close vessels is equally clear. Manyof their operations made them familiär with the fact that in this respect itseffects were similar to those of compressed air. Portions of their appa-ratus were admirably adapted to produce jets of water by means ofsteam—the mere opening of a cock to draw off the liquid Contents of aheated alembic would offen illustrate the Operation, just as the overturn-ing of an eolipile, or inclining one tili the orifice was covered with water,would do.
So far as relates to the principles of raising liquids into a vacuum formedby the condensation of steam, and forcibly ejecting them by its elasticity,nothing new was discovered by Decaus, Worcester , Savery, or Papin :both operations had long been performed with eolipiles, and were of com-mon occurrence in laboratories. 1t was in the extension of these opera-tions to hydraulic purposes that the merits of those last named consisted.‘ Draining machines’ were wholly out of the track of the transmuters ofmetals—the design of such contrivances was one which few if any ofthem would have stooped to pursue. Had they made the raising ofwater by steam a subject of particular study, hardly one of them couldhave failed to produce a machine similar to Savery’s, for every elementof it was in their possession and in constant use. ’Tis true we haveas yet referred only to the expulsion of hot water from close vessels,but the application of steam to drive cold liquidsfrom a separate vessel was not unknown. Of thisthere is an incidental but very conclusive proof ina book of Porta’s, entitled Spiritali, (named afterHeron’s work) originally published in Latin in1601, and five years after in Italian and Spanish .In the translation of 1606, is the annexed figureNo. 187, designed to show “ into how many partsa simple portion of water may be transformed”i. e. by measuring the quantity expelled from aclose vessel, by vapor evolved from a certain quan-tity heated in a retort. “ Make a box of glass ortin, (c) the bottom of which should be pierced witha hole, through which shall pass the neck of a bot-tle ( a) used for distilling, containing one or twoounces of water. The neck shall be soldered to the bottom of the boxso that nothing can escape there. From the same bottom shall proceeda pipe, ( i ) the opening of which shall almost touch it, leaving just roomenough between them for the water to run. This pipe shall pass throughan opening in the lid of the box, and extend itself on the outside to asmall distance from its surface. The box must be filled with water by afunnel (e) which is afterwards to be well closed, so as not to allow theair [steam] to escape :—finally, the bottle must be placed upon the fireand heated a little ; then the water, changed into steam, will act violentlyupon the water in the box, and will make it pass through the pipe (i) andflow off on the outside,” &c. a This apparatus although designed merelyto illustrate the relative bulk of a volume of water and that of the steaminto which it might be converted, yet exhibits in the clearest light theprinciple afterwards adopted for raising liquids by the elasticity of steam.
No. 187. A.D. 1606. Porta.