Chapter Ii., Note 27), Ramsay and Young Observed That the Ratio of

the absolute temperatures (t + 273) corresponding with equal tension varies for every pair of substances in rectilinear proportion in dependence upon t, and, therefore, for the above pressure p, Ramsay and Young determined the ratio of t + 273 for water and bromine, and found that the straight lines expressing these ratios for liquid and solid bromine intersect also at 7°·05; thus, for example, for solid bromine--

p = 20 25 30 35 40 45 273 + t = 256·4 259 261 263 264·6 266 273 + t´ = 295·3 299 302·1 304·8 307·2 309·3 c = 1·152 1·154 1·157 1·159 1·161 1·163

where t´ indicates the temperature of water corresponding with a vapour tension p, and where c is the ratio of 273 + t´ to 273 + t. The magnitude of c is evidently expressed with great accuracy by the straight line c = 1·1703 + 0·0011t. In exactly the same way we find the ratio for liquid bromine and water to be c{1} = 1·1585 + 0·00057t. The intersection of these straight lines in fact corresponds with -7°·06, which again confirms the melting point given above for bromine. In this manner it is possible with the existing store of data to accurately establish and verify_ the melting point of substances. Ramsay and Young established the thermal constants of iodine by exactly the same method.

The observations made by Paterno and Nasini (by Raoult's method,