邊度可以揾到硝酸鉀呀

Pharmacies carry potassium nitrate in bottles.
However, I do not know if they will sell to anyone these days for security reasons, because it is a component of explosives.
Also, I used to be able to get them from chemical supplies stores on Tung Man Street and Hing Lung Street in Victoria.

正字係「搵」，右邊係「����」，為「溫」的本字。����，上面係囚，下面係皿，代表食物。贈食物予囚，有如雪中送炭，受仁心感動而溫暖。與「日」無關。