B. //. Woodivard — Notes on Chemistry and Physics. 397 



form directly from their elements ; but we think the instances given 

 above are sufficient to prove that there is no natural barrier between 

 inorganic and organic compounds. This, it is needless to add, brings 

 us no nearer to the cause of life; chemistry only deals with the 

 combinations of matter. 



We use here the term '^organic chemistry" in its old sense, i.e, 

 the chemistry of organic life as distinguished from " inorganic " or 

 *' mineral chemistry." Since these discoveries the term organic 

 chemistry is more generally applied to the chemistry of carbon and 

 its compounds. 



Tlie sjaitheses, of which we have given a brief sketch above, are 

 chiefly the results of the investigations of the chemists of this 

 generation. In such a short notice it would be invidious to mention 

 names. For a more detailed account we would refer our readers to 

 the report of a lecture by Mr. Greville Williams, F.E.S., delivered 

 at the Koyal Institution on the 8th of May last, on the " Artificial 

 Formation of Organic Substances." 



In physical science also, of late, the changes in our conception of 

 the nature and mode of action of the physical forces have been very 

 considerable. Attraction, motion, heat, light, electricity, magnetism, 

 and chemical affinity, are now all considered to be affections of mat- 

 ter itself, not specific entities, as was formerly supposed ; they are 

 sometimes called modes of motion, being all resolvable either 

 directly or indirectly into motion, so also are they convertible into 

 one another. 



In other words, they are all believed to be the result of molecular 

 motion, i. e., of the motion vibratory, undulatory, or rotatory on or 

 around their axes, of the particles of matter. A molecule is the term 

 used to denote the smallest quantity of any substance, either simple 

 or compound, which can exist in a free state : thus a molecule of 

 common salt is composed of one atom of sodium united to one of 

 chlorine ; that of alcohol, of two atoms of carbon, six of hydrogen, 

 with one of oxygen : these are very simple forms, some are much 

 more complex. Matter may be still further divisible ; those bodies 

 which we look upon as elements may not be really such : it is 

 believed the medium filling space by which light, heat, etc., are con- 

 veyed, is matter in a more elementary condition. 



Let us examine the grounds on which the assumptions are based 

 that have caused these changes in our theories. 



It is well known that there are vacant spaces between the particles 

 of all matter. Almost all bodies expand when heated, and contract 

 when cooled, that is when heat is taken from them ; this is now sup- 

 posed to be owing to the greater molecular motion of the particles 

 of the bodies when heated. Most substances exist in three different 

 states, solid, liquid, and gaseous; and it is believed that all bodies 

 would do so, if we could only cool or heat them sufficiently, except- 

 ing, of course, those compounds that decompose before reaching 

 the requisite temperature. 



In solids the molecular motion is considerably overbalanced by 

 molecular cohesion : in fluids these forces are nearly balanced ; in 



