Stories About Chemistry
54. The Sun as a Chemist
Once Stephenson, the inventor of the steam locomotive, was taking a walk with his friend Beckland, a geologist, near the first railway in England. Presently they saw a train passing.
All living things owe their origin to the Sun, especially plants. Try and grow them in the dark, and all you will get is pale thin filaments instead of juicy green stalks. Under the action of solar light chlorophyll (the colouring matter of green leaves) converts the carbon dioxide of the air into complex molecules of organic substances which constitute the bulk of the plant.
Hence, the Sun, or rather its rays, are the chief “chemist” synthesizing all the organic substances in plant? It would seem so. Not in vain has the process of assimilation of carbon dioxide by plants been named photosynthesis.
It is known that many chemical reactions occur under the action of light. There is even a special branch of chemistry which studies them, called photochemistry.
But so far the study of photochemical reactions has not resulted in the creation of either proteins or hydrocarbons in the laboratory. And it is these compounds that are the primary products of photosynthesis in plants.
At the initial stage the plant uses only carbon dioxide, water and solar light for the synthesis of very complex organic molecules.
But maybe there is something else that plays a part in these processes?
Imagine a factory with soda, petroleum, potassium nitrate, etc., being fed through pipes at one end and lorries loaded with bread, sausage, and sugar driving out of its gates at the other end. This is fantasy, of course, but it is just about what happens in plants.
Plants have been found to have their catalysts, called enzymes. Each enzyme makes a reaction proceed only in a definite direction.
It appears that the Sun accomplishes photosynthesis not as the sole “chemist,” but in collaboration with his colleagues, the enzymes (catalysts). The Sun supplies the energy needed for the reaction and the enzymes make the reaction go in the right direction.
Though we cannot as yet deprive nature, and particularly plants, of their “patents” for the production of many substances, but in some cases we can already make them operate in the direction we need.
Of great value to scientists in this respect were their investigations of photosynthesis processes.
It has recently been found that if light of different wavelengths is used to illuminate the plants during photosynthesis, chemically different substances are formed. For instance, illumination with red-yellow rays results in carbohydrates as the main compounds whereas blue rays give proteins.
It may therefore be expected that in the near future people will be able, with the aid of plants, to obtain the complex organic compounds they need, on a considerable scale.
Indeed, instead of building factories, furnishing them with unique equipment and working out complex synthesis technologies, it will only be necessary to build hothouses and to regulate the intensity and spectral composition of the light rays used.
Then the plants themselves will make everything required: from the simplest carbohydrates to the most complex proteins.