Page:Treatise on Soap Making.djvu/93

77 is thus: After the leys are put in, add the tallow, and light the fire. When all the tallow is melted, put in the oil, and draw the fire a little afterwards, and allow the pan to stand about two hours. Light again the fire, and add about 20 gallons more of the leys. After the pan begins to boil, add now and then a little more leys, to the purpose of preventing the soap from boiling over: and this adding of lees to be continued until the soap is supposed to be about half boiled; when it will be time to try, whether the soap has got too much, or too little leys.

This trial is called proving, and is necessary to be done several times during the operation, and previous to the finishing. The method of performing it is this: Provide a piece of glazed Dutch delft, and also a clear clean knife: with the knife take