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.
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![and if each milligramme of this new solution contains at least one particle of dyestuff this will wcigli Icss than 0’000,000,000,000,1 grammo, thatis, less than one ten-billionth of a grammo. Wc may also confirm this result in anotlier manner : If we tako one milli- grammo of concentrated attar of roses, dissolve it in a little alcohol or etlier, pour it over a strip of tìltcr-pajìer placcd on a warm piate and move about thè room, this will he perfumed with thè cssence in a few minutcs. If we tako a largo room of a capacity of 3000 cubie metrcs (35x12x7 mctres), this is 3,000,000 litres, that is, 3,000,000,000 c.c. or tliree billion (3,000,000,000,000) cu. min., which together contain one milligrammo of thè pcrfume ; thus 1 cu. mm. contains Q-QOl 3,000,000,000,000 , that is. •000,000,000,000,000,333 grms. of pcrfume, so that cadi particle of attar of roses will certaiiily we^gli less than one-third of a thousand-billionth of a gramme. In this case thè senso of smeli is more sensitive than that of sight in thè case of coloured Solutions. In 1905, by illuminating Solutions of tluorescein with a powerful electric are, Spring deduced that thè weight of thè atom of hydrogen must he less than 2’5 x 10”21 grms. It is precisely with these hypotlietical iiifinitesimal particles that chemistry is concerned, and these are thè particles which we will study in thè various aspeets which they present to us, in their most interesting properties, forming a niarvellous world, regulated by positive and eternai laws. THE CONSERVATION OF ENERGY The principle of thè conservation of energy, or equivalence of thè various forms of energy, is thè first law of thermodynamics. We have mechanical energy (of distance, volume, surface, and movement), and non-meclianical energy (chemical, thermal, electric, and radiant energy, &c.). The vaine of each forni of energy, as we have already seen in thè case of Chemical energy, is olways expressed by thè product of thè factors of intensity and of capacity ; mechanical energy is expressed by thè product of mass and ììh \ velocity or kinetic energy y, hi thè case of thermal energy thè factor of capacity is measured by thè quantity of heat expressed hi calories and thè factor of intensity (or Ihermal potential) by thè temperature ; for energy of distance thè factors are thè distance in metres and thè force in kilograninie- metres ; for energy of volume we have volume and pressure, &c. For each forni of energy thè equivalent in other forms has been established ; thus we have thè mechanical equivalent of heat, thè electrical equivalent of mechanical energy and of heat, &c. In niany practical cases v e are able to folloi\' thè equivalent transforma- lion of llie various forms of energy, but especially in thè case of mechanical energy, which is ])resent in thè two revcrsible forms of potential energy and kinetic energy ; thè hrst is dependent 011 thè posilion occupied by a bod}q and wheii its position is changed this energy is converted into kinetic energy. If, for example, a hoavy object is 011 tlic ground and wo wisli to raise it to a beiglit of one metro by i)lacing it 011 a siij)port, wc must jJorforin a certain amount of work. But this Work is not lost, but passes into, or accuinulates in, thè raised body in that forni of energy which we cali potential enei'gy. We may soon j)rove that this energy is not lost by conneetiiig thè heavy botly by nieans of a wire with anotlier body of eipial weight, and passing thè wire over an ideal frietionless pulley, also avoiiling thè frietion of thè air. On renioviiig thè su])port of thè uj)per body a mininial impulse eauses thè upper body to deseeiul, but in descending it eairies thè lower body upwaitls by thè pulì on thè Wire. 3’he liist body has lost potential eneigy, vhieh is transfornied into energy of niotion, that is, kinetic encigy, which has served to raise exaetly thè sanie weight as had previoiisly bc!en raised by our hands. Thus we see that work has been peiiormed by transforniation of energy, which l'iicrgy has not been lost but has been transfornied froni potential energy, that is, energy of position, into actual or kinetic energy (energy of niotion).](https://iiif.wellcomecollection.org/image/b28134187_0028.jp2/full/800%2C/0/default.jpg)
