REVIEWS
Ce ii e m I On thermokinetic properties of thermodynamic potentials. 2.. -\\i?tniisoii. ,hhJ,.y, C/zeiu. 24, j o a (is97 I . -"lie author applies the tliermokinetic priiiciple to a system \\-hose state is tleterrnined by the values of unspecifieil iiitlepenclent variables p : and their differential coefficients according to the time. ant1 makes tlie same assuxnptio~isas it1 Zeit. phys. Clieni. 21, 153 i I , 37-1 escept that the impossible ant1 uiinecessary conditions that tlie differential of \wrk is done iri aii exclusively reversible manner, is dropped. Consequently the variations of the it-ork & t , , as in the case of tlie heat i Q . are divided into a reverjihle and an irreversible part. In this way a general equation is obtained from which tlie general tliermokinetic Lagrangian equations are directly tletluced. S e x t . the variables are more specified, one being chosen as the absolute temperature $. tlie other g, remaining general. The thermokiiietic priticiple applietl to this case leads to an equation which falls into two parts one of \vliich does not contain the variahle B and. is termed theisothermal form of the tlierriiokinetic principle ". -1 general fuiictioti Y of g, and 0 is defined, of ~vliicli,iini!er special assumptions. the free energy is a special case. By making the definite assumption that s 2 Q ( t h e reversible part of 8 0 , ) is equal to #AS.tlie entropy S is introduced ant1 a modified form of the isotherlnal thermokinetic principle obtained. Lastly tlie system is considered in which the independelit variahles are still moLe specialized. They are 8. the reversible part of all the dynamic coefficients Pesand sufficient other unspecified variables mh to conidefine the system a t any mornent. -1pplication of the therniokinetic le yields an equation from the three parts of which tlie corresponding Lagr:mgian equations are deduced. T h e third part contains only tlie variahles r 1 f j , and is termed the isothermal-isod?-iiatnic form of the therniokinetic priiianalogous to Y is introduced, of which, under ciple ". h general function speci.11 assuniption tlie so-called complete therniodyiianiic potential " @ is a is special case. The three Lagrange equations referred to above iii which introiluced ' ' expiess the therniokiiietic properties of this function ".
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F. R.A-. On some non-reversible processes. A . ll'nssnzuth. W i d . A?z?z. 62, ,jar L 1S97 1. - -1niatliernatical treatment of a system in which so-called friction a n d visco.;ity forces occur. -isillustration of this result the representation of elec-
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trical and magnetic phenomena by 1Iaxxrell's equations is quoted and the deduction of the latter given. F. h'. K , On alterations of state in a moving system. L. A\7antanso~~. &it. p h p . Chetz. 26, rSj (189~5'). -. Ilengthy mathematical investigation of the laws governing a system consisting of two completely imniiscible and niutually freely traiisforniable homogeneous phases in a state of motion. [The condition of inimiscihilit!. seems, in vien- of the assumed free mutual transformation ", to lack physical significance.] The treatment is based on the use of the author's ' * therniokinetic principle". At the end of the article the author gives one illustration of the application of the results in the case of a piece of ice partly dipping into a stream of water and finds that if the particles at a point in the surface of the water close to the line of contact with the ice have a velocity of one meter per second. R temperature difference of about I z m o must prevail near the line of contact. The practical application of the results to any useful physico-chetiiical prohleni is not obvious. F. 8.h-. Review : on action a t a distance. P.Drzide. W'ied. Antz. 62, 693 (1397). - " Action at a distance is said to esist hetween two bodies -1and R spatially separated from each other when .I exerts an action on R without other hotlies
effecting a continuous material connection between them ". .kccording as the word ' ' action " is construed in a purely mechanical sense or in the more general sense. as applying to alterations of condition, the definition of action at a distance +iill include ( a ) attraction of mass, forces between electrified bodies, forces between magnetized bodies, electromagnetic and electrodynamic action, or, in addition. ( h ) phenomena of the induced electric current ( i n as far as the current strength is characteristic for the condition of the body through which it flows), all phenomena of radiation (in as far. for instance, as temperature or cheniical nature can be altered by radiation). \Vith regard to the "continuous contact action may be brought ahout either through the material connection niediutn of $7-essure or by nieaiis of im$arfs. The next section (11) is devoted ( a 1 to a review of the speculative attempts to attribute action at a distance to contact action and ( b ) to a niathernatical consideration of the two classes of action. From the latter point of view the class t o which a given phenomenon belongs is simply a question of the practical expediency of taking as starting-point, on the one hand, a differential equation ( o r set of simultaneous differential equations), or, on the other, the integration of such equations. tlie latter giving the laws of action at a distance between two points in space. Section 111 gives ( 'a comparison of tlie properties of electromagnetic action and of gravitation ". Section I V is a review of investigation on the validit- of Sewton's law of gravitation, and Section T of tlie attempts to explain gravitation. The article contains excellent i1l::stratioiis both of the value and of the worthlessness of an hypothesis. F.6.K.
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On the thermodynamics of phosphorescence. h7. IVesetzdoizcR. Ivied. such phenomena as the rise i n temperature of a body at I O caused hy a fluorescing substance at oo the author sees no contradiction to the principle that heat cannot pass from a colder hod>- to a warmer one, hut
A n n . 62,706 (1897). -In
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simply a direct heating at the co?t of " Leuchteiiergie ". It appears to Iiirn also "questionable whether radiation should he treated directly as heat at all ". These ideas are, however, not new ; and have been clearly set forth by Ostwiltl I I
