Note 169 — Chapter VII · New Process for the Manufacture of Beer.

[As some confusion has existed in the nomenclature of these salts, it may be as well to offer some explanation.

The salt here used for absorbing oxygen was discovered by Schützenberger, and named by him hydrosulphite of soda. It no longer now goes by that name, being called hyposulphite of soda, NaHSO₂.

The salts formerly known as hyposulphites are now called thiosulphates, as Na₂S₂O₃.

Thus to put them together we have:—

Hyposulphite (Hydrosulphite) NaHSO₂

Bisulphite NaHSO₃

Thiosulphate (Hyposulphite) Na₂S₂O₃

The thiosulphates were formerly regarded as containing the elements of water in their composition, thus:—Na₂H₂S₂O₄, which being halved would give NaHSO₂, isomeric with hyposulphite, as Pasteur says. It is further to be observed that Pasteur uses the old notation, in which the number of atoms of sulphur and oxygen are the double of what they are in the new.—D. C. R.]