that connects the Volume of a Liquid with its Temperature. 413 
vapour of petroleum. It is unlikely that the liquids were exactly the 
same. A slight convexity directed upwards is apparent in the trend of 
the points, which a small augmentation in — would correct. 
Note D. § 4.—M. Regnault stands so high as an authority, that an 
error in his observations that can be clearly demonstrated from in- 
ternal evidence is of importance to science. Erroneous observations 
from eminent observers are serious obstacles to progress, as are un- 
sound deductions from eminent men of science. ‘They are weeds 
difficult to root up, and the attempt to do so is a task so ungracious 
and so irreverent as to incur every discouragement. 
The projection of M. Regnault’s observations on the tension of 
steam above and below 100° C. is given in fig. 8. The dotted line 
represents the empirical formula which had to be altered at 100°, 
the point at which the method employed in making the observations 
was changed. They are projected with temperatures uncorrected, in 
. the manner described in § 1 of paper in the Philosophical Magazine 
for March 1858, and they are orthographically foreshortened as de- 
- scribed in the latter part of § 4. See also § 6, and Appendix I. of 
the same paper. 
The question to ask ourselves when looking at the figure 8 is, Do 
the points conform to the law of continuity? Is their trend not clearly 
broken at 100°? To put a series of observations to the test of this 
law can always be done, but it is attended with considerable labour, 
and seems to require a speciality different from that which charac- 
terizes the eminent observer and experimentalist. 
Note E. § 6.—The following are those observations in series along 
with those of M. Despretz, both equalized graphically by elaborate 
processes, and the temperatures corrected and reduced to the air- 
thermometer. My observations from 100° up’to 212° F. agree so 
well with M. Despretz’s, that those at the higher temperatures will, I 
think, be found nearly correct, although there was some uncertainty 
in consequence of absorption by corrosion of glass. 
C. A. Volume. C.A. | Volume. C. A. Volume. C, A. Volume. 
—10 | 1-00184 || 55 | 1-:01413 |] 100 | 1-04333 || 153 | 1-09847 
— 5] 1-00068 || 6O| 1-01668 || 105 | 1-04743 || 160 | 1-10456 
0} 1:00013 || 65! 1-01940 || 110] 1-05172 || 165 | 1-11083 
51 100001 || 70) 1-02230 || 115 | 1-05620 || 170 | 1-11731 
10 | 1-00025 || 75 | 1-02538 || 120] 1-06086 || 175 | 1-12400 
15 | 1-00083 || 80! 1-02863 || 125 | 1-06570 || 180 | 1-13093 
20 | 100168 || 85 | 1-03205 || 130 | 107073 || 185 | 1-13811 
25 | 1-00280 || 90] 1-03563 || 135 | 1-07593 || 190 | 1-14553 
30 | 1:00416 || 95 | 1-03939 || 140] 1-08130 || 195 | 1-15323 
35 | 1:00575 || 100) 1-04333 || 145 | 108684 || 200 | 1-16124 
40 | 1-00755 150 | 109257 || 205 | 1-16958 
45 | 1-00955 | 210 | 1:17829 
50.| 101175 
rr rer a SS NN 
