423 



atmosphere, and the difference will in a very short time become 

 large enough to allow the surplus of production to be absorbed 

 almost as rapidly as it is formed. This is what I call a sliding 

 equilibrium. Quite analogous movements will take place in the 

 opposite direction if the consumption of CO^ should exceed 

 the production. 



It has hitherto been absolutely impossible to ascertain 

 whether the carbonic acid in the atmosphere was increasing or 

 decreasing in quantity, or perhaps remained stationary, because 

 the alteration itself must necessarily be too slow to be detected 

 by direct analysis within a reasonable space of time. The 

 method of tension-determination now furnishes a means of 

 investigating this important problem, and certain data are already 

 at hand indicating the probable result. 



1. My series of tension-determinations across the Atlantic, 

 from Cape Farewell to Fair Hill in the Shetlands, shows that 

 the tension of the Gulf-Stream and, indeed, of all Atlantic surface- 

 water in this latitude was at the time distinctly lower than thai 

 of the atmosphere. (See my preceding paper p. 403). 



2. The percentage of carbonic acid in the atmosphere 

 has been found to be lower on the high seas or at the ocean- 

 border than inland. Schulze in Rostock found for instance, by 

 a series of determinations covering several years, a mean percen- 

 tage of 0.0292 and Thorpe found on the Atlantic from Brazil to 

 England 0.0295 as a mean of 51 determinations. On the other 

 hand, FiTTBOGEN found in Brandenburg 0.0334 (average of 347 

 determinations) and Farsky in Bohemia 0.0343 (average of 295 

 determinations) M- The same difference is observed when the 

 extremely accurate English and French determinations by Arm- 

 STRONG^), Reiset^), Müntz & Aubin^) are compared with the 



') These Authors are quoted from Sai'hssk. Lehrbuch der Açirikrdtur- 



Chemie. Leipzig 1888. 

 ''] Proc. Roy. Soc. Vol. 30 p. 343. 

 3) Conqjt. rend. T. î>0 p 1144, p. 1457. 

 ••) Cotnpt. rend. ISNl. 



