122 Mr. H, A. Smith on the Chemistry of 



Experiment III. 



M . . Outside water Inside globe 



Minutes. (Fahrenheit). (Fahrenheit). 



o o 



Commencement . . 45*6 81*5 



2 ... 45-6 92-3 



6 ... 45-9 96-6 



at which temperature it remained till the end of the experiment. 

 I find, then, from this experiment that at 200° F. action com- 

 mences, that at that temperature the sulphurous acid begins to 

 act upon the nitric acid, whilst the second experiment shows 

 that the heat developed by the action itself is pretty considerable. 

 The globe was now left for twenty-four hours in the cold 

 water (see exp. II.), arid after that time had elapsed the con- 

 tents were submitted to analysis. I here give the result of three 

 analyses : — 



per cent. 



Sulphurous acid . . 6*2 1* 



Nitric acid . . . , 



Sulphuric acid . . . 9391 



100-12 

 the temperatures at time of this analysis being 



Fahrenheit. 



o 



Inside globe . . . 46*9 

 Outside water . . . 47*3 



In the above experiments it is seen that the temperature never 

 rose to the point of boiling water, but that that degree was very 

 nearly approached. 



Section IV. The Distribution of Heat in the Lead Chamber. 



We have seen in the preceding section that 200° F. is the 

 temperature at which nitric acid begins to act upon sulphurous 

 acid. I now wish to show the temperature of the lead chamber 

 in which the preceding action takes place on a large scale, and 

 then to see if I can draw some conclusion as to the best tempe- 

 rature at which to keep the sulphuric acid-chamber. 



In order to obtain a good idea of the temperature, I took daily 

 observations at different points in the chamber during a year, 

 and have condensed the results obtained into the form of diagrams. 



Ordinary maximum and minimum thermometers were em- 

 ployed ; but instead of being fixed, as usual, upon a wooden 

 back, a glass back was employed, upon which the degrees were 

 etched, and the thermometers fixed thereto by thick platinum 

 wire, thus having instruments capable of resisting all acids. 



