CONTAINED IN THE AIR ABOVE THE IRISH SEA. 153 



direct and diffused solar light, producing a corresponding 

 effect upon the vitality of sea-plants and animals, and hence 

 altering the composition of the dissolved gases. 



These conclusions of Morren are substantially confirmed 

 by Lewy^s experiments (Ann. de Chimie et de Phys. xxxv. 

 17, 1846) on the composition of the dissolved gases in the 

 water of the Channel at Langrune (Calvados) ; but the 

 two chemists differ somewhat in their statements of the 

 extent of the variations in the composition of the dissolved 

 gases. The limits of variation for the oxygen, according 

 to Morren, are from 31 to 39 in lOO volumes of the gases; 

 according to Lewy from 32*5 to 34*4. As the same 

 quantity of gas, however, is not always evolved from the 

 same volume of sea- water, but sensibly varies during the 

 day, it is better, in stating the differences between the re- 

 sults of the two observers, to compare the absolute amounts 

 evolved from the quantity of water employed in the experi- 

 ments. Thus, according to Morren, the amount of oxygen 

 varies from 297 c.cm. to 53*6 c.cm.in 4*5 litres of sea- water, 

 the amount always taken for experiment; whilst Lewy 

 finds from 23 c.cm. to 29*1 c.cm. only per 4*45 litres. In 

 regard to the carbonic acid, the variations, according to 

 Morren, are from 7*5 c.cm. to 2i-o c.cm. in 4*5 litres of 

 water; according to Lewy, from I0"6 c.cm. to ly^ c.cm. 

 in 4*45 litres. 



Morren' s determinations were made in the months of 

 March, April, and May ; those of Lewy in August and 

 September ; but this circumstance will hardly serve to ex- 

 plain the disagreement in the above results, since, as 

 the latter chemist points out, it is scarcely possible that 

 the difference in the seasons can exercise so great an in- 

 fluence. 



Both chemists, however, agree in attributing the ob- 

 served differences in the composition of the dissolved gases 

 in great part to the influence of direct and diffused solar 



