89 



CARBON. 



A series of Papers dealing with Carbon and its Compounds in their 

 Chemical, Botanical, Geographical, Geological, and Utilitarian 



aspects. 



I. 



An Outline of the Chemistry of the Element and a few of its 



Compounds. 



By Hubf^rt Painter, B.Sc, F.C.S. 



(Read before the Physical Section, Janu iry 15th, 1916.) 



rpHE lecture I have to give this afternoon is intended to be the 

 first of a series dealing with Carbon. I have, as far as is 

 possible in a single hour, to give such an account of the Chemistry 

 of Carbon as may form a useful introduction to the lectures that 

 are to follow. The subject is large, the time is short, let me begin 

 by trying to answer the question: " What is Carbon? " Briefly,. 

 Carbon is one of the chemical elements; moreover, it is that one 

 which is most characteristic of animal and vegetable substances. 

 Protoplasm has been declared to be the material basis of life ; we 

 may add to this dictum that Carbon is the material basis of 

 protoplasm. No sooner is a question answered than another, or 

 several others, arise out of the answer. Thus it may be asked : 

 " What is a chemical element? " To this I should reply: What- 

 ever views metaphysicians may hold concerning the ultimate 

 nature of matter, the chemist, for the purpose of his science and 

 within its limits, has to recognise matters rather than matter — 

 i.e., he finds there to be a relatively small number (something 

 under a hundred) of different kinds of matter. These are, so far 

 as we are at present advised, simple and inconvertible one into 

 another. Every material thing with which we are acquainted con- 

 sists of these elements, of a single one, or of two or more united 

 in that specially intimate way known as chemical combination ; or, 

 thirdly, and most frequently, of compounds mixed together. 

 Carbon occurs in nature in all these three ways. It is sometimes 

 found isolated, or, as we say, in the free state; again, pure speci- 

 mens of compounds of Carbon are sometimes met with, and, 

 lastly, complex mixtures occur containing two or a larger number 

 of carbon compounds associated, it may be, with yet other com- 

 pounds containing no carbon. In what follows I shall not confine 

 myself to substances existing ready-made in nature, but shall 



