EVOLUTION OP GASES PROM HOMOGENEOUS LIQUIDS. 



289 



limb of the U and up the other until it reached the regulating apparatus, and thus 

 turned the gas jet down, the lowering of which caused the oil to contract until the 

 regulator was opened. This process repeated itself until an equilibrium of tempera- 

 ture was reached. By means of this apparatus the temperature could easily be 

 maintained within a twentieth of a degree on either side of that required. When the 

 temperature was constant observations were commenced, the volume of gas evolved 

 during the preliminary operations being collected in some measuring apparatus. At 

 the end of the observations the mixture was heated to 100 to 110 C., and the volume 

 of the gas given off measured, in order to determine the residue of undecomposed 

 formic acid, the necessary correction being applied for the volume of air displaced by 

 the expansion of the acid mixture. An account of the conditions of one experiment 

 will serve, mutatis mutandis, for each of the successive series. A mixture was 

 made up as follows : 



150 c.c. sulphuric acid; 

 60 c.c. water ; 

 10 c.c. water containing 1 gram of sodium formate. 



The 1 gram of the salt yields 32 '9 observations of the standard unit of chemical 

 change of 10 c.c. dry carbonic oxide with the simultaneous formation of '2655 gram 

 of water, or a dilution at the completion of the reaction of '379 per cent. Some 

 quantity of gas was lost before observations were commenced, before a temperature 

 convenient for the purpose was attained ; the amount of residue at the conclusion 

 was determined as described above. 



In the following Table the results obtained are set forth, in which r represents the 

 residue at the conclusion of each successive observation; 6 l the interval of time 

 in minutes and decimals required for that observation ; and T the sum of the several 

 values of 69^, or the time from the commencement. 



SERIES I. 

 Temperature 737. 



MIXXX2LXXXVIII. A. 



2 P 



