[ 121 ] 



XVI. The Chemistry of Sulphuric Acid-manufacture. 

 By H. A. Smith. 



[Continued from p. 37.] 



Section III. On the Temperature at which Nitric Acid acts 

 upon Sulphurous Acid. 



IN Section 1. 1 gave one or two laboratory experiments show- 

 ing some of the conditions under which these gases act 

 upon each other. I now wish to show the temperature at which 

 this action takes place. These experiments were made in a 

 similar manner to the former. I took the glass globe formerly 

 used ; and into this the mixed gases were led with the addition 

 of a little water; it was then placed in another vessel containing 

 cold water, arranged so that it could be raised to any required 

 temperature, or boiled if necessary. A thermometer communi- 

 cated with the interior, its bulb being nearly in contact with the 

 water at the bottom of the globe. The temperature also of the 

 exterior water was accurately observed. At the commencement 

 of the experiment the temperatures were : — 



Experiment I. 



Fahrenheit. 



o 



Interior of globe . . . 36*7 

 Exterior water .... 40*3 



the interior being thus a little cooler than the exterior. The 

 water was now cautiously and slowly heated, the temperature 

 being observed from time to time, whilst the first formation of 

 acid in the vessel was carefully noted, the results being : — - 



Experiment II. 



, T . Outside water Inside globe t, , 



Minutes. (Fahrenheit)> (Fahrenheit). Remarks. 



o o 



Commencement. 40*3 36*7 No action, ruddy fumes. 



2 . 62-4 39 



4 . 127-6 1228 



6 . 154-3 200-2 



f Ruddy fumes begin to 

 \ disappear. 

 r Remarkably quick and 

 ^ energetic action. 



The globe was now withdrawn from the hot water in which it 

 was and again plunged in cold ; the temperature soon fell to 

 81°*5 Fahr. ; but no change took place in the action, that con- 

 tinuing as active as ever. After it had been left in the water 

 some time, it was seen that the great fall in temperature was 

 only temporary ; it soon began to rise. 



