Association of American Geologists and Naturalists. 127 



inate analysis of the several coals, he was enabled to bring to a test the 

 theoretical heating power assumed by European chemists. One interest- 

 ing result which these researches tended to establish was, that the evap- 

 orative power is dependent on the carbon constituent of coal. Six dif- 

 ferent coals, of very different constitution, were cited as affording proofs 

 of this law of heating power. 



He stated that those who have sought to determine the heating power 

 o^ fuel for practical purposes, by computing separately the heating pow- 

 ers oft pure solid carbon and that of hydrogen gas^ seemed not to have 

 taken into account the amount of heat already in a latent state in the 

 latter material, as used by chemists to determine its heating power, while 

 in fuel the material itself is in either a solid or liquid state. In illumi- 

 nating gas, (which may be used for heating purposes,) the hydrogen has 

 been rendered gaseous by the agency of a large amount of fuel, burned 

 under the retort. It was stated that the practical bearing of this differ- 

 ence becomes the more important in cases where the products of com- 

 bustion necessarily pass away from the surfaces to be heated at a tem- 

 perature above boiling point. The vapor of water thus escaping has 

 the same bulk as the hydrogen from which it has been generated, while 

 the oxygen which had been condensed in forming it possessed only one 

 half that bulk. On the other hand, the oxygen, which, with the carbon 

 of fuel, forms carbonic acid, is unchanged In volume. The carbon may 

 consequently be considered as undergoing no effective enlargement 

 when burned into that acid. In the calorimeters of Lavoisier and Rum- 

 ford, moreover, the watery vapor generated from hydrogen was conden- 

 sed by employing cold surfaces, capable of absorbing the latent heat of 

 the vapor generated in combustion, as well as the sensible heat of 

 the gases. 



On motion of Dr. Binney, it was resolved to rescind the reso- 

 lution passed last year relative to the election of officers, and to 

 proceed at once to the discharge of that function. 

 The officers for 1845 were then chosen by ballot. 

 Prof William B. Rogers was chosen Chairman. 

 Mr. B. Silliman, Jr. and Dr. J. Lawrence Smith, S^eretaries. 

 Dr. D. Houghton, Treasurer. 



BIr. John L. Hayes read a " Report on the Geographical Dis- 

 tribution and Phenomena of Volcanoes," prepared in pursuance of 

 a resolution of the Association of last year. 



He examined minutely the geographical distribution of volcanoes 

 with reference to determining the great lines of their geognostic posi- 

 tion, and demonstrated that their position was determined by the con- 

 figuration of the crust of the earth, and the outlines, extent and conti- 

 nuity of the great continental masses. 



