THE SOLUBILITY OF SULPRUR DIOXIDE ETC. 59 VII.-The Solubility of Sulphur Dioxide in Sulphuric Acid. By FRANK DOUGLAS MILES and JOSEPH FENTON. IN the course of some work on the gas-purifying system of a plant for the manufacture of sulphuric acid by the '' contact " process it was noticed that 95 per cent. sulphuric acid dissolved more sulphur 55 60 65 70 75 80 86 90 95 100 2.8 Percentage of H2S04 in aeid. dioxide than did acid of 85 per cent. The solubility in more dilute acid diminishes in the usual manner as the concentration increases, so that the observation pointed to some peculiarity in the solubility curve for higher concentrations of acid. A determination of th 60 THE SOLUBILITY OF SULPHUR DIOXIDE ETC. Sulphur dioxide dissolved by 100 Sulphuric acid. grams of acid. Per cent. Grams. 55- 1 5-13 59.6 4.90 61.6 4-82 68.9 4.1 6 74.1 3.63 78.3 3.23 80.2 13-12 82.5 2.99 84.2 2-88 85.3 2.83 85.8 2.80 86.5 12.82 Sulphur dioxide dissolved by 100 Sulphuric acid. grams of acid. Per cent. Grams. 88.1 2.9 90.8 3.10 92.8 3.2 1 93.7 3.27 94.0 3.31 94.6 3.50 95.5 3.69 95-6 3.77 96-5 3.83 98.0 3-98 98.5 4.03 - SEN AND GHOSH PHLOROACETOPHENONE. 61 'L'he solubility reaches a minimum value in sulphuric acid of 86.0 per ceut. and from that point the curve inclines very sharply upward for either increase or decrease in percentage of sulphuric acid. It is significant that acid of 84.5 per cent. has the composition of the hydrate H,SO,.H,O and that in the neighbourhood of this point the temperature of melting and other physical properties pass through critical values. [Received Decernbey 1 8th. 19 19.