Treatise on general and industrial inorganic chemistry / by Etore Molinari ; third revised and amplified Italian edition translated by Ernest Feilman.
- Ettore Molinari
- Date:
- 1912
Licence: In copyright
Credit: Treatise on general and industrial inorganic chemistry / by Etore Molinari ; third revised and amplified Italian edition translated by Ernest Feilman. Source: Wellcome Collection.
27/734
![Examples of potontial energy and of its transformation into kinetic onergy are very abundant. Tlìo inovemcnt and position of tho planotary systonis are tho inost porfcct oxamplos of conlinuons and incossant transformation of ])otcntial and kinctic onergy. A Jargo motoorito fading and giving np all its potontial onergy will ac(|niro suoli a vclooity t hat on roaching tho oarth’s surfacc it will collide witli it in a formidablo and disastrous inanncr. This doos not ordinarily happon, bocauso a part of tho onergy is givcn up to tho atmosphoro through wliicli tho motoorito is obligod to pass, witli a largo amoiint of friction, bcfore roaching tho oarth’s siirfaco, and a largo part of tho potontial onergy is thus transformcd into thormal onergy and roduocs tho volocity, so that tho meteorite is hcated and bccomos rod-hot. Evon tho hail which forms at high altitudos woiild ho broken by tho moro rosistant roofs of tho housos on which it falls if it did not impart some of its onergy to thè atmosphoro. Tho potontial onergy of fading water producos kinetic onergy in a usoful and ovidont mannor on passing botween tho blados of a turbino. But in thè small world of thè Chemical particles thè cases of potential energy are extraordinarily impressive, because in Chemical Systems enormous quantities of potential energy, or energy of position, take part. If thè confignration of our hypothetical System of Chemical particles constituting a given snbstance is modified and thè particles change their position, giving rise to another System (another snbstance), when, in short, thè particles at any given point under certain conditions approach one another in such a manner as to forni a new snbstance, then thè amount of potential energ}^ which is transformcd into kinetic energ}^ is so barge and powerfiil as to astonish the most fantastic thinker. The particles of hydrogen gas have a volocity of about two kilometres por sccond, and when they approach those of oxygen under certain external influonces—impeded by their great volocity—in such a manner as to attract and combine with them, tho potontial energ}'' is transformcd into kinetic energy giving rise to heat, light, and detonation, vith formation of water, a new snbstance. {Tmnsl%ior\s note.—The kinetic energy due to the velocity of the hydrogen and oxygen molecules is quite distinct from their potential Chemical energy, which is eiddenced in the combination. ) A few grammes of dynamito or nitroglycerine enclosed in thè interior of a rock, in changing thè position òf their particles during a Chemical rcaction produco such a quantity of kinetic energy that thè most resistant rockis shattered ; in a few seconds an amount of Avork is accomplished which hundreds of workmen conici not achieve in twenty-four hours. Kinetic energy is of mudi interest to us, espccially in its various transformations. Matter, wliich we consider as divided into very small particles, manifests itself to us by means of its energy, which may be explained as an oscillatory movement of thesc par- ticles, in the forni of continuous, uninterrupted attractions and repulsions, which rcach our scnses in thè forni of vibrations transmitted by thè ether, which is extreniely attenuated and imponderable, and fìlls the entire universe.^ Lct us suppose for a moment, with Crookes, a long thin piate of steel, fixed in thè middle of a dark rooni ; on causing the piate to oscillate gcntly all its particles v ili vibrate, ‘ In ordcr to explain Chemical phenomcna, matter has becn imaginccl to lic clivitlcd into very minute particles liaving a definite weight and volume. In order to explain certain pliysical phenomcna scicntists have had to mako use of a hypothetical snbstance very much Icss dense than thè clicmical particles, so much so as to he impon- derable, a snbstance which cxtends throughout tho universe and pcnctratcs all bodics, inclnding tho walls of glass vcsscls, (tc. This snbstance is callcd the vibratory ether or eosmic ether, and is thè medium by means of wnlch thè more important physical phenomcna, light, clcctricity, c^'C., are manifested. When one remembers that solar light rcaches us through spacc with a velocity of 300,000 kilometres per sccond, traversing regions where tlicrc is no air or otber poiidcrablc matter, it would bc impossiblc to imagine such a raiii.l trausmi-isiou withoat supposing the existenco of the vibratory ether, diffused throughout tho universe and pciictrating all bodics and all s])ace. (See beloni : Unity of Energy and Matter.) Sound is transmitted by the vibrations of thè air, and if an clcctric bell is iilaccd under an cvaeuated reeeiver the sound no longer reaehes our car, whilst, on tho contrary, thè light of an clcctric lamp under thè .sanie cvaeuated reeeiver rcaches our cye. 'J'iie transmission of tho light caniiot I)c comprclieiidcd, cxccpt by tlie liypotliesis of tlie eosmic ether. Previous to this hypothesis it was supposed that thè jiropagation of licat was due to thè detach- ment and exjmlsion of minute jiarticles from thè hot objcct, and that heat was in fact a sort of material, as was believed by Laplace (1749-1827) ; this notion causcd great confusion in chemistry and jiliysies, and retarded progress. In 1758 Le Sago had ventured tho hypothesis that heat was duo to rapii! vibrations of small particles of matter, as had jircviously been imagined by Bacon (lOOO). In 1799 B. Thomson (Count llumford) considored heat to bc a form of motion, and already ascertained with ccrtainty that heat did not affoct the weight of bodics. In 1800 Nicholson further delined the hypothesis of heat, attributing it to the vibration of the particles of matter](https://iiif.wellcomecollection.org/image/b28134187_0029.jp2/full/800%2C/0/default.jpg)
