Y4f Intelligence and Miscellaneous Articles. 



the other of 1 atom of oxide of manganese, Mn O, and 1 atom of oxide 

 of tungsten, W 0-. 



2nd. That these two compounds occur in diflFerent proportions in 

 specimens coming from different places, but that these proportions are 

 always simple atomic relations . — Ann . de Chim . et de Phys.,Aout 1 84 1 . 



ON THE GASES DISENGAGED BY MARINE PLANTS. BY M. AIME, 

 PROFESSOR OF PHYSICS AT ALGIERS. 

 Haxing frequently had occasion to observe the plants which grow 

 in the sea, M. Aime remarked that they are commonly covered with 

 a great quantity of bubbles ; and this phsenomenon is more readily 

 wsible as the water is more tranquil. In certain localities a kind of 

 froth is formed on the surface of the liquid similar to that which is 

 seen in freshwater marshes ; and M. Aime thought at first that they 

 were similar in composition, but analysis showed that this was not 

 the case. 



The formation of bubbles takes place at all times of the year, but 

 always depends on the action of light. At sunrise it is difficult to 

 collect sufficient gas for analysis, whilst on the evening of a clear 

 day the quantity is considerable : that light was the sole cause of 

 its production was proved by the fact, that plants, with their roots 

 exposed to \dvid light for a few minutes in fresh portions of sea- 

 water, immediately produced bubbles on the surface of the leaves, 

 while, if kept in the dark for a sufficient time, they disappeared. 

 These plants were kept aUve for two months and retained their 

 powers : to render this observation more conclusive, some plants on 

 the sea-shore were examined during several successive days ; after 

 sunset all the bubbles were removed by agitation, and the next morn- 

 ing they were again perceptible. No appreciable quantity of gas 

 was produced during the night, or that which was formed was im- 

 mediately dissolved by the water; whereas, as soon as the rays of 

 light fell rather vividly on the plant, the formation of bubbles oc- 

 curred. 



Every variety of plant which M. Aim6 examined was covered with 

 bubbles on the surface, but some have the additional property of form- 

 ing them internally ; they are in general plants with soft leaves, such 

 as the Ulvse, Confervae, &c. 



Light increased the bulk of these bubbles, often sufficiently so to 

 tear the leaf containing them ; darkness diminished them much, but 

 never completely destroyed them. 



The gases of the external and interior bulbs, and that obtained 

 morning and evening, were analysed, with the annexed results : — 



Oxygen. Azote. 



From the interior bubbles collected before sunrise 17 83 



after sunset 36 64 



... exterior ... before sunrise 21 79 



in the sun at 10 a.m. 55 45 



It is the last gas which forms a scum on the surface of the water 

 when it is not disturbed ; it is produced in so gieat quantity, that a 

 litre [about two pints] has often been collected by RI. Aime by agi- 



