But celluloid is only one of many plastic substances that have been introduced to the present generation.  A new and important group of them is now being opened up, the so-called “condensation products.”  If you will take down any old volume of chemical research you will find occasionally words to this effect:  “The reaction resulted in nothing but an insoluble resin which was not further investigated.”  Such a passage would be marked with a tear if chemists were given to crying over their failures.  For it is the epitaph of a buried hope.  It likely meant the loss of months of labor.  The reason the chemist did not do anything further with the gummy stuff that stuck up his test tube was because he did not know what to do with it.  It could not be dissolved, it could not be crystallized, it could not be distilled, therefore it could not be purified, analyzed and identified.

What had happened was in most cases this.  The molecule of the compound that the chemist was trying to make had combined with others of its kind to form a molecule too big to be managed by such means.  Financiers call the process a “merger.”  Chemists call it “polymerization.”  The resin was a molecular trust, indissoluble, uncontrollable and contaminating everything it touched.

But chemists—­like governments—­have learned wisdom in recent years.  They have not yet discovered in all cases how to undo the process of polymerization, or, if you prefer the financial phrase, how to unscramble the eggs.  But they have found that these molecular mergers are very useful things in their way.  For instance there is a liquid known as isoprene (C_{5}H_{8}).  This on heating or standing turns into a gum, that is nothing less than rubber, which is some multiple of C_{5}H_{8}.

For another instance there is formaldehyde, an acrid smelling gas, used as a disinfectant.  This has the simplest possible formula for a carbohydrate, CH_{2}O.  But in the leaf of a plant this molecule multiplies itself by six and turns into a sweet solid glucose (C_{6}H_{12}O_{6}), or with the loss of water into starch (C_{6}H_{10}O_{5}) or cellulose (C_{6}H_{10}O_{5}).

But formaldehyde is so insatiate that it not only combines with itself but seizes upon other substances, particularly those having an acquisitive nature like its own.  Such a substance is carbolic acid (phenol) which, as we all know, is used as a disinfectant like formaldehyde because it, too, has the power of attacking decomposable organic matter.  Now Prof.  Adolf von Baeyer discovered in 1872 that when phenol and formaldehyde were brought into contact they seized upon one another and formed a combine of unusual tenacity, that is, a resin.  But as I have said, chemists in those days were shy of resins.  Kleeberg in 1891 tried to make something out of it and W.H.  Story in 1895 went so far as to name the product “resinite,” but nothing came of it until 1909 when L.H.  Baekeland undertook a serious and systematic study of this reaction