of the world.  During the Unwashed Ages, commonly called the Dark Ages, between the destruction of the Roman baths and the construction of the modern bathroom, the art of the perfumer, like all the fine arts, suffered an eclipse.  “The odor of sanctity” was in highest esteem and what that odor was may be imagined from reading the lives of the saints.  But in the course of centuries the refinements of life began to seep back into Europe from the East by means of the Arabs and Crusaders, and chemistry, then chiefly the art of cosmetics, began to revive.  When science, the greatest democratizing agent on earth, got into action it elevated the poor to the ranks of kings and priests in the delights of the palate and the nose.  We should not despise these delights, for the pleasure they confer is greater, in amount at least, than that of the so-called higher senses.  We eat three times a day; some of us drink oftener; few of us visit the concert hall or the art gallery as often as we do the dining room.  Then, too, these primitive senses have a stronger influence upon our emotional nature than those acquired later in the course of evolution.  As Kipling puts it: 

  Smells are surer than sounds or sights
  To make your heart-strings crack.

VI

CELLULOSE

Organic compounds, on which our life and living depend, consist chiefly of four elements:  carbon, hydrogen, oxygen and nitrogen.  These compounds are sometimes hard to analyze, but when once the chemist has ascertained their constitution he can usually make them out of their elements—­if he wants to.  He will not want to do it as a business unless it pays and it will not pay unless the manufacturing process is cheaper than the natural process.  This depends primarily upon the cost of the crude materials.  What, then, is the market price of these four elements?  Oxygen and nitrogen are free as air, and as we have seen in the second chapter, their direct combination by the electric spark is possible.  Hydrogen is free in the form of water but expensive to extricate by means of the electric current.  But we need more carbon than anything else and where shall we get that?  Bits of crystallized carbon can be picked up in South Africa and elsewhere, but those who can afford to buy them prefer to wear them rather than use them in making synthetic food.  Graphite is rare and hard to melt.  We must then have recourse to the compounds of carbon.  The simplest of these, carbon dioxide, exists in the air but only four parts in ten thousand by volume.  To extract the carbon and get it into combination with the other elements would be a difficult and expensive process.  Here, then, we must call in cheap labor, the cheapest of all laborers, the plants.  Pine trees on the highlands and cotton plants on the lowlands keep their green traps set all the day long and with the captured carbon dioxide build up cellulose.  If, then, man wants