IMPROVEMENTS IN CALORIMETRIC COMBUSTION, AND THE HEAT OF COMBUSTION OF TOLUENE

Theodore W. Richards, Harold S. Davis
1917 Journal of the American Chemical Society  
The object of this investigation, which is part of a much larger program, was to secure further more precise knowledge of the heat of combustion of typical compounds of carbon, and further development of the methods of determination.' The work herein described followed directly after that detailed in the recent communication published with Dr. Frederick Barry; and the methods and apparatus resembled in most respects those already explained. Having profited by the experience of the earlier work,
more » ... f the earlier work, we were able to improve upon some of its details. Especial emphasis will be laid upon the improvements. The method consisted in the successive combustion of toluene and a standard substance in the Berthelot bomb as modified by Atwater and Benedict, in oxygen under about 22 atmospheres pressure. The rise of temperature of the colorimeter containing the bomb was paralleled in the environment, so that no correction for cooling was.needed. That this adiabatic method is capable of giving excellent relative results is shown by the series of investigation conducted at Harvard University; its absolute accuracy is proved by the recent careful work of the Bureau of Standards by H. C. Dickinson and his assistants.2 The general assemblage of apparatus is adequately described and depicted in the most recent of the preceding papers, and the reader is referred to these as regards minutiae. The details in which improvements were instituted were as follows: the mode of sealing the bomb, the mode of providing for the well regulated and complete combustion of the volatile substance; the mode of ignition; the automatic control of the temperature of the environment by a special 'synthermal regulator;' and the analysis of the residual gases for traces of unburned carbon monoxide. These several topics are discussed in order below, and finally the results for naphthalene and toluene are given. Other substances also were burned, but the details concerning these will be reserved for another communication. The closing of the bomb.-The bomb was sealed by a washer of lead, sunk in a suitable circular slot and covered by a continuous round plate of gold foil (0.4 or 0.5 mm. thick) which protected the whole inside of 50
doi:10.1021/ja02248a002 fatcat:6uvnaewnofav5hs5vtxaa2xs5u