280 



MR. V. H. VELEY ON THE CONDITIONS OF THE 



before ; these are divided into sets of 50 c.c. each, there being a small loss of gas, as 

 observed above, before the last observation of each set and the first of the next. 



Mixture used, 12 grams oxalic acid in 120 c.c. sulphuric acid. 



Temperature 68-9-69 0< 0. 



The results at the reduced pressure show an initial acceleration, then a constant, 

 followed by a gradually decreasing, rate ; when the mixed gases had filled up the 

 vacuum, which required a volume of 75 c.c., corresponding to a loss of 7'5 observa- 

 tions, the initial acceleration again repeats itself, followed by a constant rate practically 

 equal to that obtained at the point at which the pressure was increased. 



These observations do not point to any marked difference in the rate of evolution 

 of gas at pressures below the atmospheric. 



Another series of experiments was conducted under nearly identical conditions, 

 which point to the same general result. 



Temperature 66 '9-67-0. 



In the first set three observations were missed, owing to some irregularity in the 

 working of the SPBENGEL pump. 



Decomposition of Formic Acid into Carbonic Oxide and Water. 



A series of experiments was also conducted to determine the effect produced by 

 variation of pressure on this decomposition ; the method of working was the same as 

 that described above, but the twin U apparatus was used, the carbonic oxide being 



