EVOLUTION OF GASES FROM HOMOGENEOUS LIQUIDS. 



2G3 



In order to determine the effect produced by variation of the mass of pumice, an 

 experiment precisely similar to the one described above was conducted ; in one flask 

 was placed '1 gram, in the other 5'0 grams of pumice. Temperature 76. 



The rate of evolution of gas from both mixtures is proceeding pari passu ; thus 

 the mass of pumice added, whether '1 gram or fifty times that amount, makes no 

 difference. 



The effect of finely divided particles, not only upon the decomposition of formic 

 acid into carbonic oxide and water, but also upon other chemical reactions in which a 

 gas is evolved, was studied more fully by aid of the twin U-tube apparatus. 



Decomposition of Formic Acid into Carbonic Oxide and Water. 

 HCOOH = CO + 



Effect of Graphite. 



Mixture taken 



175 c.c. sulphuric acid. 

 75 water. 



Into this was filtered slowly 50 c.c. of an aqueous solution of sodium formate, con- 

 taining 5 grams of the salt. From this quantity 165 observations of 10 c.c. each 

 are obtainable, so that in the earlier stages of the decomposition the effect due to loss 

 of mass in each successive observation is inconsiderable. 



After a preliminary stage of initial acceleration (see Part II.), the rate of evolution 

 of gas became constant ; when this point was reached, the cork through which passed 

 the thermometer was taken out and about half a gram of finely-powdered graphite 

 was introduced into the mixture ; the containing flask was shaken, the cork restored 

 to its former position, and observations recommenced at the same temperature. 



Temperature 80'5-807. 



