Figure 13. The refraction of light shows a coin at the bottom of a cup (picture). JOY was used as a detergent

From

Practical Chemistry of Long-Lasting Bubbles

Momoko Ueno, Naho Isokawa, Kazuki Fueda, Suzuka Nakahara, Hinako Teshima, Nanami Yamamoto, Haruka Yokoyama, Yukina Noritsugu, Koushi Shibata, Kourin Miyagawa, Seiko Tanaka, Takashi Hirano, Ayako Fujito, Ayaka Takashima, Kenichi Kanno

World Journal of Chemical Education. 2016, 4(2), 32-44 doi:10.12691/wjce-4-2-2