BRIDGMAN. — THERMODYNAMIC PROPERTIES OF WATER. 311 



derivatives are therefore completely (letcriniiied, so that wc now have 

 all the (lata at hand for the determination of any one of the thermo- 

 dynamic properties of the liquid. This means that we are in a posi- 

 tion to find such quantities as the specific heats, change of internal 

 energy, adiabatic temperature rise etc., as well as the more easily 

 determined compressihility and thermal dilatation. The latter part 

 of the paper, after the discussion of the method and the presentation 

 of the data in the first part, is occupied with the computation of these 

 various thermodynamic quantities. The accuracy of some of these 

 is probably not very great, because the error in the second derivative 

 of an experimental quantity may be considerable. It has, therefore, 

 seemed best to give the general view of the nature of the quantities 

 which is offered by a graphical representation, rather than to give 

 tables, with the tacit assumption of greater accuracy which usually 

 goes with a set of tables. In spite of the lower order of accuracy of 

 some of these thermodynamic quantities, it has still seemed well 

 worth while to give them, since even the general trend of some of the 

 quantities, such as the specific heats, has not been hitherto known 

 with relation to pressure. 



The data presented here are only the beginning of a projected 

 stud}' of the characteristic surface under high pressures for a number 

 of liquids. The measurements have already been carried through for 

 twelve other liquids beside water. The purpose of this study is 

 ultimately the development of a theory of liquids, since it would seem 

 that a much more intimate grasp of the nature of the forces at work 

 in a liquid would be afforded by a study over a wide pressure range, 

 than over the comparatively low pressures hitherto used. It must be 

 admitted, however, that this broader purpose is not particularly 

 furthered by this work on water, because of the well known abnor- 

 malities of this substance. In the previous paper several abnormali- 

 ties had been shown to exist at low pressures. In this paper, new 

 abnormalities are found at higher pressures. Water gives the ap- 

 pearance of becoming completely normal only at the higher tempera- 

 tures and pressures of the range used here, but of course whether this 

 is really normal or not cannot be told until the behavior of normal 

 liquids has been discovered. The full significance of the present 

 data, in their bearing on such questions as the pol^-merization of the 

 liquid, for example, cannot appear until after the discovery of the 

 laws for entirely normal liquifls. The investigation of water before 

 that of normal liquids was undertaken for two reasons; firstly because 

 of the desire to complete the work for water already begun, and 



