CONTAINED IN THE AIR ABOVE THE IRISH SEA. 



155 



Hour. 



Temp, 

 of air. 



Temp, 

 of sea. 



Weather. 



Lat. & long. 

 W. (Paris). 



Distance 



of 

 continent 



Means of 3 expts. 



CO2. 



Oxygen. 



3 A.M. 

 3 P-M. 



C. 



2i°-5 



24°'0 



not 

 given 

 24-5 



Fine breeze, 

 unclouded. 



Do. slightly 

 clouded... 



o / o / 



21 45 41 3 

 21 9 42 25 



leagues. 

 435 



412 



3'346 

 5-420 



2096'i39 

 2io6'099 



The extent of this variation^ as seen from the above 

 Table^ is 2*074 for the carbonic acid^ and 9"96o for the 

 oxygen in lOjOOO volumes of air, — without doubt a very- 

 appreciable difference. 



This remarkable phenomenon may doubtless be accounted 

 for_, without any reference to the direct action of infusoria, 

 by the heating effect of the sun on the sea- water, and the 

 consequent disengagement during the day of gas propor- 

 tionately rich in carbonic acid and oxygen. During the 

 night, on the other hand, as this source of action is re- 

 moved, the disengagement may be assumed not to occur ; 

 and, following Lewy, one may perceive that this difference 

 would become more appreciable and easier to trace in air at 

 great distances from any continent than in air collected 

 nearer the coasts, and consequently liable to be mixed 

 with the air of the land. 



The specimens of air for the above experiments were col- 

 lected in glass tubes of about 100 c.cm. capacity, in the 

 manner prescribed by Eegnault in his " Instructions " to 

 the sailors and others who aided him in collecting the air 

 for his memorable research on the composition of the air 

 at different parts of the globe. The analyses were executed 

 eighteen or twenty months after, with the eudiometric ap- 

 paratus of E-egnault and Eeiset ; and the results are the 

 means of three separate determinations of each specimen 

 of air. The precision of the results in the case of carbonic 

 acid is somewhat remarkable when we consider the difS. 

 culty generally experienced in accurately noting contrac- 



