294 



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



SERIES VII. 



I 190 c.c. sulphuric acid 

 Conditions < 38'8 c.c. water. 



5'0 c.c. water containing '5 gram sodium formate. 

 Temperature 6 8 '6. 



With the exception of the last observation but one, the observed and calculated 

 results are very concordant ; thus, whether the time required for the evolution of the 

 10 c.c. of dry carbonic oxide be rather less than half an hour or sixteen hours, the law 

 governing this chemical reaction is still exemplified. 



GENERAL CONCLUSIONS. 



(i.) The rate of evolution of gases from homogeneous liquids is accelerated by the 

 presence of finely divided chemically inert particles, not only when the gas is merely 

 dissolved in the liquid but also when it is in a state of formation as a resultant of a 

 chemical reaction. 



(ii.) In the earlier stages of a chemical reaction yielding a gas the phenomenon of 

 initial acceleration is observed, the rate of change increasing up to a maximum and 

 constant point, from which it decreases at a rate bearing some immediate relation to 

 the diminution of mass. 



This phenomenon of initial acceleration repeats itself when the temperature is 

 lowered temporarily and then restored to its former point, or when the pressure 

 is increased suddenly. 



(iii.) Reduction of pressure from one to a small fraction of an atmosphere causes 

 but little permanent variation in the rate of evolution of gas from a liquid ; though a 

 sudden increase of pressure stops temporarily the evolution of gas, and a decrease of 

 pressure produces temporarily an increase in the rate of evolution. 



