444 



Drs. Ramsay and Young on 



The lines of equal volume calculated from these values of 

 a and b are reproduced graphically in Plates VIII. and IX. 

 We propose to discuss the form of the diagram later. 



We have calculated the values of p for various isothermals, 

 at the above volumes. These are shown in Plate VII. ; the 

 actual experimental observations, of which a detailed account 

 is given in the ' Philosophical Transactions/ 1886, p. 10 et 

 seq., are represented by circles. It is evident that the curves 

 through the calculated points represent the actual measure- 

 ments very closely, indeed as nearly as unavoidable error of 

 experiment allows. It is to be noticed that the greatest 

 divergence is at the temperatures 250° and 280°, but the de- 

 viations are in opposite directions, and must therefore be 

 ascribed to experimental error. 



Table III. (pp. 442, 443) gives the data from which the cal- 

 culated isothermals were constructed. 



As volumes above 30 cubic centim. per gram are not given 

 in the diagram, we have thought it advisable to show the cor- 

 respondence of calculated and observed results by a table ; 

 the calculated numbers were read from curves specially con- 

 structed from the formula p = bt — a, and the observed results 

 are those actually furnished by our experiments. It will be 

 seen that the correspondence is very close. 



Table III. (continued). 

 Temperature 100°. 



Volume. 



Pressure 

 found. 



Pres. cal- 

 culated. 



Yolume. 



Pressure 

 found. 



Pres. cal- 

 culated. 



c. c. 

 54-06 

 55-50 

 56-95 

 59-84 

 62-73 

 65-63 

 68-56 

 71-48 



millim. 

 4817 

 4720 

 4627 

 4434 

 4265 

 4102 

 3946 

 3818 



millim. 



4875 

 4760 

 4670 

 4470 

 4290 

 4100 

 3970 

 3815 



c. c. 



74-42 

 7734 

 8314 

 86-02 

 88 89 

 94-63 

 9751 



millim. 



3668 

 3546 

 3334 

 3243 

 3150 

 2978 

 2893 



millim. 

 3685 

 3550 

 3320 

 3215 

 3120 

 2970 

 2900 



Temperature 150°. 



31-09 

 33-94 

 39-66 

 45-43 

 51-23 

 5702 

 62-81 



9066 

 8497 

 7484 

 6674 

 6024 

 5480 

 5034 



9110 



8520 

 7505 

 6745 

 6100 

 5560 

 5090 



68-64 

 74-51 

 80-35 

 86-13 

 91-87 

 97-63 



4651 

 4304 

 4027 

 3783 

 3564 

 3375 



4675 

 4310 

 4010 

 3760 

 3530 

 3345 



