1R0M WOOD AiND Co VI - J| 



period of each experiment, the results will not be affected 



thereby. 



The accuracy with which the experiments have been per- 

 formed, is a delicate subject for me to expatiate upon, but 1 

 shall be permitted to say. that all means within my power 

 have been used to render the results as accurate as the difficult 

 nature of the subject will admit. These results will I"- found 

 in the general table. 



From the diversity in these results, il is apparent, that equal 

 weights of different combustible bodies vary materially in the 

 quantity of heat disengaged in their combustion. The woods 

 dilfer less perhaps in equal weights than has been generally sup- 

 posed, and that difference will Ik- found to correspond very nearrj 

 with the different quantities of carbon they contain; they an 

 however of very different value in equal quantities />;/ measurt .in 

 consequence of the great disparity in their weight. This remark 

 is also applicable to those coals which are sold by measure and 

 not by weight, from which circumstance, it becomes necessary 

 to caution those who would attempt to ascertain the value oi 

 different articles of fuel by merely comparing their different 

 results of heat in the table, without regard to (heir different 

 weights. The results being comparisons between articles in 

 equal weights, cannot be compared with quantities by measure 

 alone; hence the necessity of determining the weights of a 

 given bulk of those articles Bold in fliis manner, which will be 

 found in the table in their respective columns, the manner of 

 obtaining which will be hereafter detailed. The object of my 

 experiments being practical utility, rather than scientific re- 

 search, to facilitate the accomplishment of that desirable 

 object, I have estimated the comparative values of the different 

 articles. These will be found in the last column of the table, 

 and are equally applicable not only to every market, bul for 

 every change in the prices thai can take place. 



The standard taken N shell-bark hickory, that being of 

 greater weight than a cord of any other wood in the tabli . and 

 disengaging in its combustion an equal quantity of beat froB 

 any given weight 



vol. m. — r 



