Significats de permanent hardness en anglès

The total hardness of water is therefore commonly made up of temporary and permanent hardness.

Indeed, in the phraseology of a water-analyst, I may say that the sap itself has 25 degrees of total, permanent hardness.

Such heaters are frequently used with a reagent for precipitating permanent hardness in the combined heat and chemical treatment of feed water.

Extravasion under the skin, especially in the lower extremities may be followed by permanent hardness (induration) and stiffness due to connective tissue infiltration (scurvy sclerosis).

Permanent hardness is caused by other compounds of lime that are not precipitated by boiling the water.