22 For though thou wash thee with nitre [more likely carbonate of soda], and take thee much soap, yet thine iniquity is marked before me, saith Adonai Yahweh.
" Nitre ."
-A sister of an experimental turn of mind, after reading Prov. 25:20 , tried the experiment of putting vinegar upon nitre, but failed to produce any such disagreeable effervescence as the comparison in the proverb requires.
The following extract from a lecture by a Rabbi at "Jew's College" will interest her and others.
"In the book of Proverbs 25:20 we find it said, that
'as vinegar upon nitre, so is he that singeth songs to a heavy heart.'
We should expect from this statement that when we put vinegar upon what we call nitre, it would produce some commotion analogous to the excitement of song-singing. But we should try the experiment in vain, for no effect whatever would be produced.
...we should expect that the use of nitre would increase the purifying power of soap, but the experiment would prove rather the reverse..
The chemist, however, informs us that there is a substance, namely the carbonate of soda , which if substituted for the nitre, would effervesce with vinegar and aid the purifying power of soap, and thus strikingly illustrate the thought both of Solomon and Jeremiah.
And on recurring to the original, we find that nehther (nitrum, natrum) does not necessarily mean the salt which we call nitre, but rather a fossil alkali, the natrum of the ancients, and the carbonate of soda of the moderns."
The Christadelphian, Aug 1889