Zinc is naturally present in water. The average zinc concentration in seawater is 0.6-5 ppb. Rivers generally contain between 5 and 10 ppb zinc. Algae contain 20-700 ppm, sea fish and shells contain 3-25 ppm, oysters contain 100-900 ppm and lobsters contain 7-50 ppm.
Cyanides (more exactly as cyanogenic glycozides) exist in cassavaroots, and fruit seeds as apricots, prunes, peaches, almonds etc. Cyanide is historically found in the seeds â¦of some fruits. Applesseeds contain cyanide, but a person would have to eat a lot ofapple seeds for the cyanide to have any negative effects. Cyanide is natural found in certain foods. This includes cassava,almonds, pits of some types of fruit, and Lima beans.
15th December 2011, 03:58 AM #2. If memory serves me correctly (and at my age, if often doesn't) Potassium Ferricyanide (I don't know the difference between ferricyanide and cyanide) was used in tintype photography as well as in some print toners. of course tintype photography was late 19th to very early 20th Century. think the most used was potassium ferricyanide, a salt of potassium (duh!) and a complex of cyanide and ferric ions ([Fe(CN)6]-3). Ferricyanide in itself is not that dangerous if handled properly, but can liberate cyanide gas (HCN) under certain conditions. The latter is highly toxic.