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.
48/734
![-By cumbining iiito a single eqiuition thè two expressioiis wliich represent thè liiws of Boyle and of Gay-Lussac, for a gas of volume v at pressure p, and a temperature of t on thè ordinary scale, we obtain thè (jeneral aquation for gases : y.v = (1 + at), or, silice a = ;\ve may write ^ i ó it\ D 'V = py.Vy I 1 + -^] and tliis corresponds equally to p.v = + t) \ ^ i ó J Zi i ó but thè factor 273 + t indicates thè absolute temperature T, so tliat \ve may write T. *v The factor has a Constant vaine li, which is equal for all gases v hat- Zio ever their Chemical nature may he, if for thè vaine v e select thè molecular volume, tliat is, thè volume in cubie centimetres at 0° and 760 mm. pressure, which a quantity of gas aa ould occuj^y, thè Aveight of A\hich Avas equal to its molecular Aveight ex- pressed in grammes (gramme - molecule, abbreviated to Mol.) ; then thè final and generai formula for gases becomes : p.v = li.T. According to Avo- gadro’s laAv thè mole- cular volume of all perfect gases at 0* and 760 mm. pressure is always 22,412 c.c., tliat is, 2 grms. of hydrogen or 32 grms. of oxygen, and so on, occupy 22,412 c.c., and may t hen be represent ed by B. The figure Avhich represents thè vaine li is, as aa e have said, independent of thè nature of thè gas, but varies Ai itli thè units of measurement AA'hich A\ e select to represent thè niagnitude p and thè molecular volume ; if AA e measure thè pressure in units of one atmosphere (p^, = 1) and thè molecular Amlume in litres (that is, 22’412 litres), then E = 22-412 ^73~ 0'0821 and thus p.v = 0-0821 T. If instead of thè pressure p, that is, one atmosphere, A\ e express it in corre- sponding grammes of mercury (76 c.c. of mercury — 1033‘3 grms.), and thè molecular volume in c.c. (22,412), then thè vaine of thè gas Constant becomes : li = 1033-3 X 22412 273 84,780 and thus p.v = 84,780 T. In thè generai formula for gases pv = ET, A\e knoA\’ that pv represents a quantity of energy, namely, thè energy of volume, A\hich is independent of thè volume and thè pressure for any gas A\hatever and is oiily determined by thè absolute temperature T. That is to say, that pv represents thè quantity of energy (in absolute units)^ necessary for thè conversion of a gramnie- * AUisolulti pn’nsuì'cs aro iìiosbuios oxprosiioil iu absolute units of tlio iutoniational System, thè ceiitiiuetro- graiimio-socond (C.U.S.) System. 'J'ho dyne is the imit of foreo wliieh causes aii aeoeleratiou of 1 em. per see. per see. on 1 grm. of matter at tlie sea-level at a Jatitmle of 45“. It is known tbat gravitation produees an aeeele- ratiou of 'J81 em. por see. per see. on J gnu. of Jiiatter, and (lius a weiglit of 1 gnu. expressed in absolute units of foree eorrcsponds to USI dynes. 'J’iie pressure of 1 atmosphere eorrespojuls to a eolumu of mereury 7li em. liigli with a eross-seetion of 1 s»i. em. per sq. em., that is, to a weight of 1033 grms. and therefore to 081 x 1033 dynes, i.e. about one milliou dynes or iU dynes. And as the work eorresi»onding to the unit of foree (tlie dyne) is eaJled tlie erg (thè absolute unit of work), the pressure of an atmosphere e.xpressed in absolute uidts of work will be 10 ciya, or, more cxactly, 1,033,300 erga. (Transldtor’s note.—Tliis should read “ work dono agaiust atmospherie l»ressure through a distauee of 1 eeutimetre,”)](https://iiif.wellcomecollection.org/image/b28134187_0050.jp2/full/800%2C/0/default.jpg)
