ACTION OF CONCENTRATED SULPHURIC ACID ON IRON, 65 



In the first determinations the gases after explosion and 

 measurement were again passed into the KOH pipette to 

 see if any gases soluble therein (such as 00 3 ) had been 

 formed by the explosion. In no case was a contraction in 

 volume here obtained, hence it was concluded that no 

 appreciable quantity of methane or any other gas insoluble 

 in KOH itself, and which would give C0 3 on explosion, was 

 originally present in the gas. After observing the con- 

 traction in a duplicate explosion, the excess of oxygen was 

 absorbed in alkaline pyrogallol as a check on the subsequent 

 calculations. Two thirds of the diminution in volume due 

 to the explosion represented the volume of hydrogen in the 

 volume of gas diluted with air. The detailed order of 

 analysis was as follows : — ■ 



Original volume of gas and temperature °0. 

 Volume after absorption in KOH ,, 

 Volume after absorption in Pyro. ,, 

 Any volume of remainder „ 



Volume after addition of air „ 



Volume after explosion ,, 



In the following tables of analyses of gases evolved, 

 sulphur dioxide and hydrogen are expressed as percentages 

 of gas evolved, i.e., S0 2 and hydrogen add up to 100. This 

 affords an easier comparison than if the amount of air 

 determined was included in the tables, since for different 

 experiments the actual analyses show varying amounts of 

 air. The air found in the gases is simply the air which was 

 in the flask at start, and had been carried over along with 

 the SO 2 and hydrogen into the measuring cylinder, and was 

 estimated as stated in order to make sure that all the con- 

 stituents of the gaseous mixture were being ascertained. 

 As the gases were analysed at frequent intervals in order 

 to see if the composition changed with the lapse of time, 

 in most cases only 25 c. cms. were available for analysis. 



E-June 4, 1913. 



