Temperature *~ad if * Tension of Vapours, 



mo 



a. 



pp. 



T°. 



a. 



pp. 



- 30 



- 25 



- 20 



- 15 



- 10 



- 5 

 



+ 5 

 10 

 15 

 20 

 25 

 30 

 35 

 40 

 45 

 50 

 55 

 60 

 65 

 70 

 75 

 80 

 85 

 90 

 95 

 100 



177983 

 17-5508 

 17-3105 

 170797 

 16-8580 

 16-6421 

 16-4345 

 16-2323 

 16-0376 

 15-8478 

 15-6649 

 15-4864 

 15-3123 

 15-1457 

 14-9821 

 14-8236 

 14-6705 

 14-5208 

 14-3761 

 14-2345 

 140975 

 13-9634 

 138317 

 13-7048 

 13-5818 

 13-4610 

 13-3442 



495 

 481 

 462 

 444 

 432 

 415 

 404 

 389 

 379 

 366 

 357 

 348 

 333 

 327 

 317 

 306 

 299 

 290 

 283 

 274 

 268 

 263 

 254 

 246 

 242 

 234 



100 

 105 

 110 

 115 

 120 

 125 

 130 

 135 

 140 

 145 

 150 

 155 

 160 

 165 

 170 

 175 

 180 

 185 

 190 

 195 

 200 

 205 

 210 

 215 

 220 

 225 

 230 



13-3442 

 13-2294 

 13-1182 

 130091 

 12-9033 

 12-7994 

 12-6972 

 12-5982 

 12-5022 

 12-4077 

 12-3150 

 122259 

 12-1383 

 120521 

 11-9685 

 11-8861 

 11-8050 

 11-7260 

 11-6492 

 11-5739 

 1 1-5005 

 11-4285 

 11-3580 

 11-2891 

 11-2218 

 111554 

 110898 



230 

 222 

 218 

 212 



208 

 204 

 198 

 192 

 189 

 186 

 178 

 175 

 172 

 167 

 165 

 162 

 158 

 154 

 151 

 147 

 144 

 141 

 138 

 135 

 133 

 131 



The numbers in the third column (pp) are proportional parts of 

 one degree of the thermometer. Suppose, for example, we wish 

 to calculate the tension at 6°*74; we multiply 389, the propor- 

 tional number situated between 5° and 10°, by 1*74, the excess 

 of 6°*74 over 5°. The product 677, being subtracted from 

 16*2323, gives us the desired value of a = 16*1646. The corre- 

 sponding tension is found =7*26 millims. Regnault obtained 

 by observation 7*25, and by calculation from the formula which 

 he adopted 7*36. 



By means of an equation of the form 



«=A + Blogn + C(logn)*-, .... (10) 

 wherein n expresses the tension in atmospheres, the values of a 

 can be represented as functions of the pressure of the vapour. 

 If we make 



A= 13-3442, 



B= -1-493037, logB = 0-1740705, 



C = -0*0513, log C=0-7101174-2, 



the values of a between 100° and 230° are obtained with great 

 accuracy. We thus possess ourselves of a tolerably simple mode 

 of calculation for the determination of the temperature corre- 

 sponding to any chosen tension of vapour, the formula (9), on 



