Each element has a characteristic atomic spectrum, due to the absorption and emission of light associated with the unique energy levels of its orbiting electrons.

It is said that chlorinated drinking water brought to troops in the First World War saved more lives than were lost to the gas as a weapon.

It is through this cultural life rather than through experimental encounter in a laboratory that we really come to know the elements individually, and it is a cause for sadness that most chemistry teaching does so little to acknowledge this rich existence.

Edwin Hubble escaped the glare of ‘Orange county’ by retreating to a mountaintop observatory north of Pasadena, where he recorded the motions of the galaxies that led to his discovery of the expanding universe. But it wasn’t sodium that caused him difficulties. Potassium burns with a mauve flame which can sometimes be seen in a gunpowder explosion or when lighting a match. One night Hubble was excited to detect a potassium spectrum while he examined the galaxies through the world’s most powerful telescope. But it soon became apparent that the reading must be false. Eventually Hubble realized that the equipment had picked up the light from the potassium in the match that he had used to light his pipe.

These big pieces and headdresses, I see them more as abstractions than as subjects.

We must reiterate that the Principles are published as a discussion document and as an aide for clients and contractors alongside their in-house standard contracts and industry published standard contracts. Each IMCA member is, of course, free to negotiate their own terms, qualify such contracts and to make use of the Principles should it wish to do so in order to achieve a contract satisfactory to both parties.