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Borax commonly denotes hydrated sodium tetraborate, conventionally written $\mathrm{N}{\mathrm{a}}_2{\mathrm{B}}_4{\mathrm{O}}_7\cdot 10{\mathrm{H}}_2\mathrm{O}$ for the decahydrate. Anhydrous and other hydrated sodium borates are distinct materials, so a mass-based chemical calculation must state the hydration form.^[ref]

The decahydrate's formal formula counts ten waters per tetraborate formula unit. Those waters contribute to its molar mass and change the amount of borate delivered by a weighed sample. In solution, acid–base equilibria and pH influence the distribution of boron-containing species; the crystalline formula does not require every dissolved boron unit to remain as one unchanged anion.

César Lattes improved the measurement of particle tracks in nuclear emulsions and helped establish the pion-muon decay sequence. His own recollection describes range–energy calibrations and plates exposed at high altitude. Plates treated with borax preserved substantially more latent events than untreated controls, an unexpected practical advantage. More complete stopping-and-decay tracks then supported a comparison of the parent and daughter masses, showing why detector chemistry and calibration mattered to a particle discovery.^[ref]

A physicist.^[ref]