The amount of hydrocyanic acid in a solution may be determined by adding excess of caustic potash and a small quantity of an alkaline chloride, and running into the dilute solution standard silver nitrate until a faint permanent turbidity (of silver chloride) is produced, that is, until the reaction, 2KNC+AgNO 3 = KAg(NC) 2 - -KNO 3, is completed.
The colour of ocean water far from land is an almost pure blue, and all the variations of tint towards green are the result of local disturbances, the usual cause being turbidity of some kind, and this in the high seas is almost always due to swarms of plankton.
There is a distinct relationship between colour and transparency in the ocean; the most transparent water which is the most free from plankton is always the purest blue, while an increasing turbidity is usually associated with an increasing tint of green.
Cloudy amber maybe clarified in an oil-bath, as the oil fills the numerous pores to which the turbidity is due.
Fol and Sarasin detected the last traces of sunlight in the western Mediterranean at a depth of 254 to 260 fathoms, and Luksch in the eastern Mediterranean at 328 fathoms and in the Red Sea at 273 fathoms. The chief cause of the different depths to which light penetrates in sea-water is the varying turbidity due to the presence of mineral particles in suspension or to plankton.