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October 8th. 



ORDINARY MEETING.— MR. BENJAMIN LOMAX ON 

 "FACTS IN THE CHEMISTRY OF PLANTS." 



Altbougli tbe chemical changes which the life history of every 

 plant involved were discussed in most scientific works, and the 

 number of organic compounds directly obtained from a vegetable 

 source was recognised by all conversant with our manufactures, 

 there remained an amount of chemical effect wrought on surround- 

 ing nature by the agency of plants which altogether escaped 

 popular notice, and was apt to be under estimated even by the 

 naturalist. He must leave to those who had better opportunities 

 than himself the task of adding to their knowledge on this point, 

 contenting himself with a reference to some facts with which all 

 were acquainted, but few thought of in this connection, and 

 trusting to the after discussion for further information. The 

 evolution of oxygen by plants had been so exhaustively considered 

 in botanical works that he should merely draw attention to the 

 amount of work it actually represented. Every human being gave 

 off, on an average, 1541bs. weight of pure carbon per annum. 

 Assuming the population of the world at 20,000,000,000, the 

 wonderful amount of 137 millions and a half of tons of carbon 

 was ■ expired from human lungs alone in one year. Add to this 

 the carbon evolved from animals, lai-ge, small, and microscopic, 

 the products of combustion, and the decomposition of organic 

 matter, and some idea might be formed of the work which plants 

 had to perform ; and which they did so well that the amount of 

 carbonic acid in the atmosphere was seldom, if ever, perceptibly 

 increased. 



The deposition of silica on the exterior surface of the culm in 

 the cereals, sedges, and bamboo, might be, perhaps, regarded as 

 necessary for the stability of the plant, but the geology of certain 

 districts must be considerably modified by the change this forma- 

 tion indicated. Silica was usually found in a coarse, crystalline 



