192 NATURE AND LIFE. 



of hydrogen, carbon, and oxygen, neither acid nor alkaline, 

 which may be regarded as the result of the union of a 

 hydrocarburet with the elements of water. Common alco- 

 hol, or spirits of wine, is the type of the most impor- 

 tant series of alcohols, that of the mono-atomic alcohols. 

 Chemists represent it by the formula C 2 H 6 O, to indicate 

 that a molecule of it arises from the union of two atoms of 

 carbon with six atoms of hydrogen and one of oxygen. 

 Independently of the alcohols, which are of great number 

 and varying complexity, organic chemistry recognizes an- 

 other class of bodies, of which vinegar is the type, and 

 which receive the name of organic acids, to mark their 

 resemblance to mineral acids, such as oil of vitriol or aqua- 

 fortis. Now, every alcohol, on losing a certain amount of 

 hydrogen, gives rise to a new body, which is called an 

 aldehyde ; and every alcohol, on combining with an acid, 

 produces what is called an ether. These rapid details allow 

 us to understand precisely the chemical character of the 

 essences or essential oils which plants elaborate within their 

 delicate tissue. Except a small number among them which 

 contain sulphur, as the essences of the family of crucifers, 

 they all present the same qualitative composition carbon 

 and hydrogen, with or without oxygen. Between one and 

 another of them merely the proportion of these three com- 

 posing elements varies, by regular gradations, but so as 

 always to correspond either to a hydrocarburet, or to an 

 aldehyde, or to an ether. In this case, as in almost the 

 whole of organic chemistry, every thing is in the quantity of 

 the composing elements. The quality is of so little im- 

 portance to Nature, that, while following always the same 

 laws, and constantly using the same materials, she can, 

 by merely changing the ponderable relations of the latter, 

 produce, by ni} T riads of various combinations, myriads of 

 substances which have no resemblance to each other. The 

 strange powers of the elements and the mysterious forces 



