Association of Americaii Geologists and Naturalists. 105 



bear this fact in mind, as he might in his researches fall in with the 

 path of some ancient TJnio. 



Adjourned to 7J o'clock in the evening. 



Thursday J 7^ o^clock, P. M. — A note was read from P?'of. A. 

 D. Backe, inviting the Association to call at the office of the 

 Coast Survey, and see the instruments and work. 



Prof. H. D. Rogers submitted a communication on the prob- 

 able constitution of the atmosphere at the period of the forma- 

 tion of the coal. He stated that the recent researches of Ameri- 

 can geologists, by informing us of the true quantity of coal in 

 North America, enables us for the first time to estimate with 

 some precision its total amount on the globe, and tJiereby to 

 compute the quantity of carbonic acid which the ancient atmos- 

 phere must have contained to supply this vast body of carbon. 

 He showed that the existing atmosphere contains, in its carbonic 

 acid, carbon enough to furnish, through vegetable action, about 

 850,000,000,000 tons of coal ; and that the probable quantity of 

 coal in existence, all of which must have been elaborated from 

 the ancient atmosphere, is nearly 5,000,000.000,000 tons, that is 

 to say, about six times that which the present atmosphere could 

 produce. So great a reduction in the carbonic acid of the earth's 

 atmosphere, implying, as all chemists are aware, a corresponding 

 augmentation of oxygen, is a fact of great interest to geology, 

 as showing that very modification in the constitution of the air 

 which would adapt it to the development of animals progressively 

 higher in the scale of organization, which are known to require 

 a more rapid oxygenation of their blood. 



Prof. W. B. Rogers communicated an abstract of a paper re- 

 lating to the chemical equivalents of certain substances, as in- 

 ferred from recent experiments by Prof R. E. Rogers and him- 

 self. Referring to the progress of investigation in this funda- 

 mental branch of chemical science, he called attention to the 

 recent admirable researches of M. Dumas and other European 

 chemists, as giving strong confirmation to the doctrine maintain- 

 ed by Dr. Prout, of England, that the equivalent numbers of 

 all chemical substances are whole numbers, taking hydrogen as 

 unity. Employing the apparatus for the analysis of carbonates 

 described by himself and Prof. R. E. Rogers in Vol. xlvi, p. 346, 

 of this Journal, he stated the following as some of the results: 

 the equivalent of Ume 28, that of baryta 72, that of soda 31. A 



Vol. xLvii, No. 1.— Apvil-June, 1844. 14 



