542 M. H. Karsten on the Oxidation of Gaseous 



carbonic acid, gaseous hydrocarbons and other volatile products, 

 as yet for the most part only imperfectly known. When oxygen 

 is completely excluded, they remain unchanged under water*. 



After the completion of my former investigation, it still re- 

 mained to determine the manner in which the gaseous hydro- 

 carbons produced by the process of putrefaction, and the other 

 gaseous and solid organic bodies (odorous substances, &c.) which 

 are also present in the air, behave when they are diffused through 

 the atmosphere — a problem of the greatest importance in relation 

 to the vital process of the animal organism. 



The results of my former experiments rendered it probable 

 that these hydrocarbons would be acted on by contact with free 

 oxygen in the same way as others, but it still seemed desirable 

 to confirm this supposition by experiment. 



Two methods presented themselves for the attainment of this 

 object, which, as supplementary to each other, required both to 

 be carried out. 



In the first place, atmospheric air which still contains volatile 

 hydrocarbons, when passed through a series of vessels filled alter- 

 nately with air and with lime-water, must give up carbonic acid 

 to the lime-water until all the hydrocarbons contained in it are 

 oxidized ; and the quantity of carbonic acid deposited in the first 

 vessel must be greater than the quantity deposited in those which 

 follow, if the intervening spaces filled with air are of equal size. 



In the second place, if atmospheric air laden with hydro- 

 carbons is heated to redness, it must deposit carbonic acid only 

 in the first vessel containing lime-water or potash, and, when 

 thus freed from carbonic acid, it ought not to deposit anything 

 in the succeeding vessels. Experiments had already been made 

 according to the first of these two methods by Messrs. C. W. 

 Eliot and Frank H. Storer; but as these chemists had in view 

 the solution of another problem, and as I did not know whe- 

 ther in their experiments, which were carried out very carefully 

 in other respects, the contact of the air operated upon with the 

 organic substances, such as cork and caoutchouc, used for con- 

 necting the various parts of the apparatus was avoided (a 

 circumstance which must necessarily have affected the result), I 

 repeated the experiments myself. 



In doing so I made use of a series of vessels similar to one 

 another, one of which is represented in the accompanying figure, 

 connected together in such a way that the air in passing through 

 * During the course of the experiments here published, the evolution 

 of carburetted hydrogen and carbonic oxide gases by living plants was 

 observed by Boussingault (Compt. Rend. Nov. 1861); and the presence of 

 a large quantity of solid organic matter in the air, which remains suspended 

 when the air is in motion, was pointed out by Pasteur (Annates de Ckimie 

 et de Physique, 3rd series, vol. lxiv. p. 24, January 1862). 



