Scheele's Green

Scheele's Green, also called Schloss Green, is chemically a paints but has since fallen out of use due to its toxicity.

Scheele's Green was invented in 1775 by Carl Wilhelm Scheele. ^[1] By the end of the 19th century, it virtually replaced the older green pigments based on copper carbonate.

Scheele's original method of preparing the compound was dissolving copper sulfate, then letting it stand. The pigment precipitated, the liquid was poured off, the pigment was washed and dried on gentle heat.

Scheele's Green was more brilliant and durable than the then-used copper carbonate pigments. However it tended to fade and blacken when subjected to hydrogen sulfide containing atmosphere. It also can not be mixed with pigments based on sulfides or containing sulfur.

Paris Green, was developed later in attempt to improve Scheele's Green. It had the same tendency to blacken, but was even more durable.

By the end of 19th century, both greens were made obsolete by zinc oxide and cobalt green, also known as zinc green.

Scheele's Green was used as an insecticide in 1930's, together with Paris Green.

Scheele's Green can be used also to color wax candles. There is one example of an acute poisoning of children attending a Christmas party where such candles were burned.^[2]

Scheele's Green was used as a color for paper, eg. for wallpapers and paper hangings, and in paints, even on some children toys.^[3] It was also used to dye cotton and linen. The wallpapers containing Scheele's Green are implicated in the arsine gas.

Despite its high toxicity, Scheele's Green was also used as a chrome yellow, used for sweets, snuff and custard powder.

References

1. ^ http://www.lilinks.com/mara/history.html
2. ^ http://www.harvestfields.ca/HerbBooks/01/01/047.htm
3. ^ http://www.gutenberg.org/dirs/etext04/dvmth10.txt
4. ^ http://www.chemistry.ucsc.edu/teaching/Winter97/BMB150C/lecture3.html