136 
PROFESSOR W. RAMSAY AND DR, S. YOUNG 
name “orthobaric” as applicable to such a curve, and “ orthothermic ” to denote the 
curve representing relations between volumes and pressures at temperatures cor¬ 
responding to the vapour-pressures of the substance. 
18. It would be possible to obtain the volumes of 1 gram of the liquid at definite 
temperatures and at corresponding vapour-pressures directly from the “ orthobaric ” 
curve, or by constructing new isothermals, by means of the isobaric curves, for such 
temperatures and reading the points of intersection of such curves with the “ ortho¬ 
thermic ” curve. Since the results for the temperatures of observation were practically 
identical, it was judged sufficient to read them directly from the “ orthobaric” curve. 
19. The numbers thus read are as follows ;— 
Specific Volumes * and Specific Gravities of Alcohol at Definite Temperatures, and 
at the Vapour-pressures corresponding to these Temperatures. 
T. 
Sp. v. 
Sp. gr. 
T. 
Sp. v. 
Sp. gr. 
O 
110 
1-417 
0-7057 
O 
225 
2-094 
0-4775 
120 
1-444 
0-6925 
230 
2-198 
0-4550 
130 
1-473 
0-6789 
232 
2-250 
0-4444 
140 
1-508 
0-6631 
234 
2-314 
0-4292 
150 
1-541 
0-6489 
236 
2-390 
0-4184 
160 
1-580 
0-6329 
237 
2-435 
0-4107 
170 
1-622 
0-6165 
238 
2-483 
0-4027 
180 
1-671 
0-5984 
239 
2-541 
0-3935 
190 
1-7295 
0-5782 
240 
2-614 
0-3825 
200 
1-796 
0-5568 
241 
2-699 
0'3705 
210 
1-890 
0-5291 
242 
2-820 
0-3546 
220 
2-017 
0-4958 
242-5 
2-925 
0-3419 
20. For the sake of comparison, we give Hirn’s (‘ Annales,’ (4), 10, p. 32) and 
Mendelejeff’s ( loc. cit.) numbers. 
Mendelejeff . . T=130‘9 o (V 0 =l); 1T895. Found (R. and Y.) IT90. 
Hirn .T= 150-0° (V 0 =l); 1'24074. Found (R. and Y.) R243. 
Zuk also, loc. cit., gives numbers for the volumes of alcohol. These have already 
been considered. 
Specific Volumes and Specific Gravities of Saturated Vapour of Alcohol. 
21. It has been explained in § 5 how the volume of the saturated vapour was 
measured, and the various corrections introduced. We now proceed to give the 
experimental numbers. 
* As some confusion has been introduced by the use of the phrase “ specific volume ” as synonymous 
with “atomic” or “molecular volume,” it should here be stated that the expression is employed to 
denote the volume of 1 grm. of the substance. 
