RESEARCHES UPON THE CHEMICAL PROPERTIES OF GASES. 221 



VI. QUANTITATIVE ANALYSIS OF NATURAL GAS. 



It is not possible to determine the proportion of the individual paraffins in a gas 

 mixture by the Bunsen method of explosion of oxygen unless it can be positively 

 asserted that only two paraffins occur. This may be readily shown by an example. 

 If a mixture of one volume each of marsh gas, ethane and propane is burnt, the vol- 

 umes of oxygen required, carbon dioxide and steam produced will be as follows : 



OXYGEN KEQUIRED. CO^. H.fi VAPOR. 



1 vol. methane 2 vols. 1 vol. 3 vols. 



1 " ethane 3^ " 3 " 3 " 



1 " propane 5 " 3 " 4 " 



lOJ " 6 " 9 " 



Three volumes of ethane require for combustion ten and one-half volumes of 

 oxygen, and yield six volumes CO2 and nine volumes of steam. 



Hence a mixture of three gaseous paraffins could not be distinguished, in the 

 case of a volumetric analysis, from the intermediate paraffin. Moreover, the heat of 

 combustion of three volumes of the intermediate paraffin is almost exactly equal to 

 that of a mixture of one volume each of the three. 



From the fact last stated it follows that, as regards the calorific value of a mix- 

 ture of paraffins, an exact determination of the character of the individual paraffins 

 is not required. 



A saving of time, the possibility of using a larger volume of gas, the avoidance 

 of a volumetric determination of water vapor, are some of the advantages gained by 

 a combustion over copper oxide. 



The application of gravimetric methods for the examination of gas is not new. 

 "Winkler (HandhooJc of Technical Gas Analysis, p. 87) has described such a process 

 for the analysis of mine gas. 



Description of Method. — The process employed was, with some slight modifica- 

 tions, the same as described in the Annual Report of the Geological Survey of 

 Pennsylvania for 1886. 



Glass cylinders having stop-cocks at both ends, accurately calibrated by mer- 

 cury and of 300-400 c.c. capacity, were filled with natural gas. Where possible, 

 this was done at the well. Before filling with gas, finely drawn-out threads of 

 glacial phosphoric acid were inserted through the stop-cock into the vessel. After 

 twenty-four hours the gas sample could be considered dry. 



Glacial phosphoric acid, on softening in the flame, may be readily drawn out 



A. P. S. — YOL. XVII. 2 0. 



