EJIylSHA MITCHE^IvIv SCIEJNTIFIC SOCIEJTY. 27 



about 200 cc.) confined in the flask, had been utilized in 

 the formation of the copper sulphate produced. Accord- 

 ing- to the formula o-iven above; the oxyg-en would be ab- 

 sorbed and no corresponding- amount of any other g-as 

 would be eliminated; consequently there should a g-reater 

 external pressure at the close than at the beg-inning- of 

 the experiment. When the smoothly ^tting- g-lass stopper 

 was removed, not only no extra external pressure was 

 noticed, but in' fact a pressure from within. This was 

 evidently produced by the sulphur dioxide g-enerated. 

 The sulphur dioxide was swept out by a current of air 

 throug-h a dilute solution of potassium permang-anate, 

 which was quickly bleached. The presence of sulphur 

 dioxide was further proven by the addition of barium 

 chloride to th^ bleached potassium permang-anate solu- 

 tion. Nor does the formula g-iven above account for the 

 cuprous sulphide which is always produced. 



Second experimoit. — Realizing- the possibility of some 

 org-anic matter or dust remaining- in the flask, althoug-h 

 it had been carefully cleansed, the first experiment was 

 repeated with the g-reatest precaution to ensure the ab- 

 sence^of Must. The flask was scoured with boiling- con- 

 centrated|pure sulphuric acid containing- potassium bi- 

 chromate and carefully cleansed with distilled water. 

 The last Jtraces of water were removed by four subse- 

 quent washing's with the same kind of concentrated acid 

 used- thro ug-hout the experiments. The experiment was 

 carried out in the same manner as the first, the same re- 

 sults being- obtained. 



A blank experiment was carried out at the same time. 

 The. 'flask was rendered dust free in the manner just 

 mentioned and fifty cc. of the same acid allowed to re- 

 main in the flask for six months. At the end of that 

 period not a trace of sulphur dioxide could be detected in 

 the blank, therefore the sulphur dioxide produced when 

 the^copper was inserted could not be due to the reduction 

 of the sulphuric acid by an extraneous substance, but 



