Proverbs 25:20

As vinegar upon nitre - The original word nather is what is known among chemists as the natron of the ancients and of the Scriptures, and carbonate of soda. It is found native in Syria and India, and occurs as an efflorescence on the soil. In Tripoli it is found in crystalline incrustations of from one third to half an inch thiek. It is found also in solution in the water of some lakes in Egypt and Hungary. The borders of these lakes are covered with crystalline masses, of a grayish white or light brown color; and in some specimens the natron is nearly pure carbonate of soda, and the carbonate is easily discovered by effervescing with an acid. It appears to have its Hebrew name from nathar , to dissolve or loosen: because a solution of it in water is abstersive, taking out spots, etc. It is used in the East for the purposes of washing. If vinegar be poured on it, Dr. Shaw says a strong fermentation immediately takes place, which illustrates what Solomon says here: "The singing of songs to a heavy heart is like vinegar upon natron:" that is, "there is no affinity between them; and opposition, colluctation, and strife, are occasioned by any attempt to unite them." And poureth vyneper upon chalke - Coverdale. This also will occasion an effervescence. See Jeremiah 2:22.