biborate

Boric acid in aqueous or glycerine solutions, and borax (biborate of soda) are sometimes used, but care is necessary in employing these substances, as any excess is liable to decompose the soap.

The Handbook of Soap Manufacture H. A. Appleton

We have here a most interesting subject to solve as to the component parts of the ancient natron; my suspicion is that natron, as used by the Egyptians, was a mixture of biborate of soda, caustic soda, and muriate of soda.

Practical Taxidermy A manual of instruction to the amateur in collecting, preserving, and setting up natural history specimens of all kinds. To which is added a chapter upon the pictorial arrangement of museums. With additional instructions in modelling and artistic taxidermy. Montagu Browne

~Borax~ is a hydrated biborate of soda, containing nearly half its weight of water.

A Text-book of Assaying: For the Use of Those Connected with Mines. Cornelius Beringer 1886

Earth containing biborate of lime is brought to this place all the way from Wadsworth, in the State of Nevada -- a very great distance, with several transhipments -- to be reduced at these works; and it seems that this can be more cheaply done here than there, where they have neither wood for the fires nor soda for the operation.

Northern California, Oregon, and the Sandwich Islands Charles Nordhoff 1865

The efflorescing matter is composed of carbonate of soda, chloride of sodium, and biborate of soda.

Northern California, Oregon, and the Sandwich Islands Charles Nordhoff 1865

Then a biborate of soda was prepared; and this, I think, is an unobjectionable case.

Experimental Researches in Electricity, Volume 1 Michael Faraday 1829