326 ANNUAL OP SCIENTIFIC DISCOVERY. 



TOBACCO AND ITS RESULTS. 



MR. ROBERT ELLIS, in editing the official catalogue of the Great Ex- 

 hibition, makes the following remarks concerning tobacco: "The 

 total quantity of tobacco retained for English consumption in 1848, 

 amounted to nearly 17,000,000 Ibs. North America alone produces 

 upwards of 200,000,000 Ibs. The combustion of this mass of vegetable 

 matter would yield about 340,000,000 Ibs. of carbonic acid gas ; so 

 that the yearly increase of carbonic acid gas from tobacco smoke alone 

 cannot be less than 1,000,000 Ibs., a large contribution to the annual 

 demand for this gas made upon the atmosphere for the vegetation of 

 the world." 



VALUE OF FLAX TO GREAT BRITAIN. 



IT is estimated that there is yearly consumed in the linen and other 

 manufactures of Great Britain, 100,000 tons of flax. Of this quantity 

 75,000 tons are imported, the remaining 25,000 tons being the pro- 

 duce of the British isles. The total value of all the articles of British 

 manufacture, in which the flax fibre imported is employed, exceeds 

 5,000,000 annually. 



Flax-seed for sowing and crushing is imported annually into Great 

 Britain, to the amount of 1,820,000, taking the quantity imported 

 050,000 quarters, at 7s. per quarter ; 70,000 tons of oil-cake, for feed- 

 ing of cattle, having a value of 600,000, are also imported yearly. 



VEGETABLE PHYSIOLOGY. 



MM. does and Gratiolet, in some experiments upon aquatic plants, 

 as species Potamoge ton, Confervas,, and the like, obtain the following 

 results : Influence of light. The disengagement of oxygen from 

 the green part of plants is very rapid in full solar light, insensible in 

 diffuse light, and null in darkness ; and in the last condition no car- 

 bonic acid is disengaged, contrary to an old opinion, but now for some 

 years correctly understood. With glass of different colors, the effect 

 was greatest with colorless glass, and diminished in the order, red, 

 green, blue. Influence of temperature. The decomposition of car- 

 bonic acid by aquatic plants, exposed to light under a temperature of 

 -{- 4 C., does not commence until the temperature is raised to 15 0., 

 and has its maximum at 30 C.; and if the plants are in a temperature 

 of 30 C., then, on its reduction, action continues even to 10 C. This 

 result corresponds with Chevreul's on the circulation and ascension 

 of the sap of plants. Influence of the composition of the surrounding 

 ivatcrs. In river water, deprived of air by ebullition, and containing 

 only carbonic acid in the same proportions as the waters of the Seine, 

 the water being frequently renewed, the decomposition is at first 

 active, but afterwards diminishes, and ceases after four or five days ; 

 and by this time the green color of the plant has become paler. At 

 first the gas produced is mixed with some nitrogen, the quantity of 

 which goes on diminishing ; so that when decomposition ceases, the 



