The journal of the Royal Society of 1671 carried a review of a paper by a Dr Caroli de la Font entitled ‘The nature and causes of the plague’ in which he put forward the theory that it was due to ‘arsenic exhalations’ that were polluting the air. Of course he was wrong, but the idea that such emissions could pollute the atmosphere was not wrong and 150 years later, in 1821, they may well have contributed to the death of one of the great figures of history: Napoleon. Arsenic had, and still has, its uses as we saw in the previous chapter but it is an insidious element and is much more mobile than earlier generations appreciated. When it diffuses into the air we breathe, and gets into the water we drink it causes problems and in this chapter we will look at two ways that it led to – and is still leading to – mass poisonings. The historical story concerns its leakage from wallpaper, the modern story concerns its leakage from underground rocks. The first of these leakages contaminated the air of millions of homes in the Victorian age, the second contaminates the drinking water of millions of people in Bangladesh and neighbouring states of India today. The first of these tragedies was eventually controlled, the second one remains to be dealt with. In days gone by the palette of a painter might well have held three arsenic compounds because they could provide brilliant shades of yellow, red, and especially green. The first two of these came from the natural pigments yellow orpiment and red realgar, both of which are arsenic sulphides; orpiment has the formula As2S3, and realgar has the formula As4S4. Orpiment got its name from the Latin words auri (gold) and pigmentum (paint) and was popular in the ancient world, especially in the Middle East. Its association with gold is probably what made it attractive to alchemists. Orpiment only became widely used in Europe when synthetic orpiment was manufactured and then it was known as royal yellow or king’s yellow and was the preferred source of yellow until it was displaced by chrome yellow (lead chromate) and cadmium yellow (cadmium sulphide).
Drinking water purity – a UK perspective
