history of nanobiotechnology.

1. THE PURPLE OF
CASSIUS
BY KRATI AGARWAL

2. What is the purple of Cassius?
• Color used in glazing of –
earthenware, glass,
porcelain, and enamels.
• One of the most ancient
and beautiful colors.

3. • Chemical composition- oxide of tin
oxide of gold
water
• Variation in the amount of either metal gives various
shades- red, purple, violet.
• Method also used to test the presence of gold.
• Intensity of color tells the amount of gold.

4. HISTORY-
• Discovered by the German physician,
Andreas Cassius of Leyden in 1685.
• His book- De Auro
• Detailed study- Berzelius.
• But, the purple precipitate method
was given by his father 25 years
before.
• Compound of gold could impart a
red color to glass- known for
centuries by Egyptians.
• By the early 1720s reached China.

5. PREPARATION-
• “Absorption of colloidal gold (Au) particles by stannic acid (𝐻2𝑆𝑛𝑂3)
creates a purple solution known as the Purple of Cassius.”
• Stannic acid – hydrated tin oxide.

7. IS IT EXPENSIVE???
*Copper- dead black of cuprous oxide

8. THANK YOU !!!