378 Description of an Apparatus for the 



chemical philosopher to -decide the controverted question re- 

 specting their composition. Results, sufficiently multipli- 

 ed and precise for this purpose, would require a larger ap- 

 propriation of time, than I have the prospect of being able 

 to bestow ; and I can only, on the present occasion, offer an 

 example of the method in which it appears to me that the 

 analysis of this class of substances will be most successfully 

 attempted. 



When a vegetable substance, composed (as may be as- 

 sumed to simplify the statement) of oxygen, hydrogen, and 

 carbon, united in the form of a ternary compound, is sub- 

 mitted to distillation, at a temperature not below that of ig- 

 nition, the equilibrium of affinities, which constituted the 

 triple combination, is destroyed ; and the elements, com- 

 posing it, are united in a new manner. Those, which are 

 disposed to enter into permanently elastic combinations, 

 escape in the state of gas. The carbon, uniting with oxy- 

 gen, either composes carbonic acid gas, or, stopping short 

 of that degree of oxygenation which is essential to change 

 it into an acid, is converted into carbonic oxide. The hy- 

 drogen, combining with a portion of carbon, constitutes a 

 binary com pound of those two ingredients, forming either 

 what has been called carbureted hydrogen gas, or super- 

 carbureted hydrogen, better known by the appellation of 

 olefiant gas. Towards the close of the process, a portion of 

 simple hydrogen gas is also mingled with the products. Per- 

 haps in no instance is any one of the gases, which have been 

 enumerated, obtained perfectly pure, by the distillation of a 

 vegetable substance. The aeriform fluids,- which are thus 

 generated, are found to be possessed of almost every degree 

 of specific gravity ; and to yield, by combustion, extremely 

 different results, according to the temperature at which they 

 have been formed ; the stage of the process at which they 

 have been separated ; and other modifying circumstances. It 

 becomes an interesting question, whether these gases, so 

 much diversified in their physical and chemical properties, are 

 mixtures of a few binary compounds, with which chemists 

 are already acquainted ; or whether, on the contrary, their 

 elements are capable of uniting in indefinite proportions . arid 

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