ORGANIC MATTER. H 



very high temperatures. The oils and fats also are readily car- 

 bonized by heat. Resinous and gummy substances are easily 

 made to render up some of their constituents. And the 

 alcohols, with their allies, have no great power of resisting 

 decomposition. These bodies, formed by the union of 



oxygen, hydrogen, and carbon, are also, as a class, chemi- 

 cally inactive. Formic and acetic are doubtless energetic 

 acids; but the higher members of the fatty-acid series are 

 easily separated from the bases with which they combine. 

 Saccharic acid, too, is an acid of considerable power; and 

 sundry of the vegetable acids possess a certain activity, though 

 an activity far less than that of the mineral acids. But 

 throughout the rest of the group, there is shown but a small 

 tendency to combine with other bodies; and such combina- 

 tions as are formed have usually little permanence. 



The phenomena of isomerism and polymerism are of fre- 

 quent occurrence in these triatomic compounds. Starch and 

 dextrine are probably polymeric. Fruit-sugar and grape- 

 sugar, mannite and sorbite, cane-sugar and milk-sugar, are 

 isomeric. Sundry of the vegetal acids exhibit similar modi- 

 fications. And among the resins and gums, with their 

 derivatives, molecular re-arrangements of this kind are not 

 uncommon. 



One further fact respecting these compounds of carbon, 

 oxygen and hydrogen, should be mentioned; namely, that 

 they are divisible into two classes — the one consisting of 

 substances that result from the destructive decomposition of 

 organic matter, and the other consisting of substances that 

 exist as such in organic matter. These two classes of sub- 

 stances exhibit, in different degrees, the properties to which 

 we have been directing our attention. The lower alcohols, 

 their allies and derivatives, which possess greater molecular 

 mobility and chemical stability than the rest of these tri- 

 atomic compounds, are rarely found in animal or vegetal 

 bodies. While the sugars and amylaceous substances, the 

 fixed oils and fats, the gums and resins, which have all of 



