NATURAL PHILOSOPHY. 137 



negative p6le, which, although multiplied by the duration of the current, are 

 yet very sparingly developed. 



la the second mixture, the proportions were three parts of the anhydrous 

 acid to one of the acid SQ3 + HO. This gives a solution of better conduct- 

 ing power. As in the former experiment, oxygen appears at the positive 

 pole, but much more copiously ; and at the negative pole a slight escape of 

 gas-bubbles is perceptible, whilst the blue streaks present themselves in 

 greater quantity, coloring the liquid contained in the negative arm of the 

 tube. The odor of sulphurous acid is also distinctly perceptible. With the 

 continuance of the action the temperature rapidly rises, the escape of gas 

 at the negative pole is more abundant, and sulphurous acid is formed; but 

 the blue streaks, however, diminish when the tube is immersed in water 

 gradually heated, and disappear altogether at 140 Fah., while a more copious 

 formation of sulphurous acid sets in. As the tube containing the electrolyte 

 gradually cools, the color reappears. 



This whole process is effected much more rapidly when the mixture is in 

 the proportion of two parts of the anhydrous to one of 80s + HO, or of 

 equal parts of both, the temperature being kept at 32 Fah. The blue color 

 at the negative pole clearly proves that sulphur is liberated there, the solution 

 resembling that obtained by dissolving sulphur in anhydrous sulphuric acid. 

 Of this fact, the temperature at which decomposition takes place, and the 

 formation of 80s, furnish sufficient testimony independent of the color 

 produced. 



The development of sulphurous acid seems to be occasioned by the rise 

 of temperature produced in the solution by the action of the current. Nor 

 is it confined to the negative arm of the tube; circumstances which indicate 

 that it is a secondary product. 



In regard to the sulphur which has been observed at the negative pole, 

 there are only two ways of accounting for its presence. It is either the result 

 of direct decomposition by the current, or of the reducing action of the 

 liberated hydrogen. 



The combination 80s with HO, according to Faraday, is decomposed into 

 sulphur and hydrogen at one electrode, and oxygen at the other. The same 

 combination subjected to the action of the battery by Genther, gave at first 

 only H and O at their proper poles; sulphur was liberated only when the 

 temperature of the electrolyte was considerably raised by the action of the 

 current. When the tube was placed in water kept at 32 Fah., the liberation 

 of oxygen and hydrogen was of longer duration before free sulphur ap- 

 peared. The temperature of the electrolyte was found to rise almost instan- 

 taneously with the removal of the tube from the water. This would seem 

 to indicate that by keeping the electrolyte at 32, the liberation of sulphur 

 would be prevented, which shows the great influence temperature has on the 

 product of the decomposition. It was further observed that the odor of sul- 

 phurous acid accompanied the liberation of sulphur, owing probably to the 

 action of S on the warm sulphuric acid. If we assume that in this process 

 the liberation of the sulphur is due to the reducing action of H, then it con- 

 sistently follows that the H, endowed with so strong an affinity, must unite 

 with the sulphur it meets at the moment of separation, and form sulphuretted 

 hydrogen. Not a trace of this gas has however been yet detected. Further- 

 more, if the hydrogen could exert this reducing action, it would at most be 

 but the reducing of SOs to SO2- With such proofs drawn from experiment, 

 we must assume the direct decomposition by the current of sulphuric acid 



12* 



