I9i Mr. Faraday on some ^lexc Products 



tions. It is therefore an object in the analysis of oil and coal 

 gas, to possess means by which their presence and quantity 

 may be*ascertained ; and this I find may be done with con- 

 siderable exactness by the use of sulphuric acid, oil, &c., in 

 consequence of their solvent power over them. 



Sulphuric acid is in this respect a very excellent agent. It 

 acts upon all these substances instantly, evolving no sul- 

 phurous acid ; and though when the quantity of substance is 

 considerable as compared with the acid, a body is left unde- 

 composed by or uncombined with the acid, and volatile, so 

 as constantly to afford a certain portion of vapour ; yet when 

 the original substance is in small quantity, as where it exists 

 in vapour in a given volume of gas, this does not interfere, in 

 consequence of the solubility of the vapour of the new com- 

 pound produced by the action of the acid in the acid itself in 

 small quantities : and I found that when 1 volume of the va- 

 pour of any of the products of the oil gas liquor was acted 

 upon, either alone, or mixed with 1, 2, 3, 4, up to 12 volumes 

 of air, oxygen, or hydrogen, by from half a volume to a volume 

 of sulphuric acid, it was entirely absorbed and removed. 



When olefiant gas is present, additional care is required in 

 analytical experiments, in consequence of the gradual combi- 

 nation of the olefiant gas with the sulphuric acid. I found 

 that 1 volume of sulphuric acid in abundance of olefiant gas, 

 absorbed about 7 volumes in twenty-four hours in the dull 

 light of a room ; sunshine seemed to increase the action a 

 little. When the olefiant gas was diluted with air or hydro- 

 gen, the quantitjr absorbed in a given time was much dimi- 

 nished ; and in those cases it was hardly appreciable in two 

 hours, a length of time which appears to be quite sufficient fbr 

 the removal of any of the peculiar vapours from oil or coal gas. 



My mode of operating was generally in glass tubes over 

 clean mercury'-', introducing the gas, vapour or mixture, and 

 then throwing up the sulphuric acid by means of a bent tube 

 with a bulb blown in it, passing the acid through the mercury 

 by the force of the mouth. The following results are given 

 as illustrations of the process : 



Oil Gas from a Gasometer. dimin. 



sul. acid in 8' inlhoiir 2 hours per cent. 



188 vol. + 9-5 vol. diminished to 1550 148-5 14G-4 22-12 



107 + 13-0 88-5 84-5 82-0 23-33 



138 + 5-2 113-7 1080 106-5 22-82 



• If the mercury contain oxidizable metals, the sulphuric acid acts upon 

 it, and evolves sulphurous acid gas. It may be cleaned sufficiently by being 

 left in contact with sulphuric acid for twenty-four hours, agitating it fre- 

 quently at intervals. 



Oil 



