EXAMPLES OF. 325 



ialr, it absorbs two equivalents of oxygen, and is con- 

 tverted into benzoic acid; but half of the oxygen ab- 

 sorbed combines with the hydrogen of the oil, and 

 forms water, which remains in union with the anhy- 

 drous benzoic acid.* 



But, although it appears very probable that the 

 oxygen acts primarily and principally upon hydro- 

 gen, the most combustible constituent of organic 

 matter in the state of decay ; still it cannot thence 

 be concluded, that the carbon is quite devoid of the 

 power to unite with oxygen, when every particle of 

 it is surrounded with hydrogen, an element with 

 which the oxygen combines with greater facility. 



We know, on the contrary, that although nitrogen 

 cannot be made to combine with oxygen directly, yet 

 it is oxidized and forms nitric acid, when mixed 

 with a large quantity of hydrogen, and burned in 

 oxygen gas. In this case its affinity is evidently- 

 increased by the combustion of the hydrogen, which 

 is in fact communicated to it. It is conceivable, 

 that in a similar manner, the carbon may be directly 

 oxidized in several cases, obtaining from its con- 

 tact with hydrogen in eremacausis a property which 

 it does not itself possess at common temperatures. 

 But the formation of carbonic acid during the ere- 

 macausis of bodies containing hydrogen, must in 

 most cases be ascribed to another cause. It appears 



* According to the experiments of Dobereiner, 100 parts of pyrogal- 

 lic acid absorb 38-09 parts of oxygen when in contact with ammonia 

 and water ; the acid being changed in consequence of this absorption 

 into a mouldy substance, which contains less oxygen than the acid it- 

 self. It is evident, that the substance which is formed is not a higher 

 oxide ; and it is found, on comparing the quantity of the oxygen ab- 

 sorbed with that of the hydrogen contained in the acid, that they are 

 exactly in the proportions for forming water. 



VS^hen colorless orcin is exposed together with ammonia to the con- 

 tact of oxygen gas, the beautiful red-colored orcein is produced. Now;,, 

 the only changes which take place here are, that the absorption of oxy- 

 gen by the elements of orcin and ammonia causes the formation of 

 water ; 1 equivalent of orcin C18 H12 08, and 1 equivalent of ammo- 

 nia NHS, absorb 5 equivalents of oxygen, and 5 equivalents of water 

 are produced, the composition of orcein being C18 HIO 08 N. (Du- 

 mas ) In this case it is evident, that the oxygen absorbed has united 

 merely with the hydrogen. — L. 



28 



