1913 N. S. Finzi Radium Therapeutics ii. 17 One Mache unit = 4.5 × 10⁻¹⁰[sic] Curies... It may be mentioned here that the waters of Gastein, the strongest natural radioactive spring, contain less than 250 Mache units per litre.

1915 C. E. S. Phillips in R. Knox Radiogr. ii. 343 Some confusion appears to have crept into the interpretation of the relationship between the curie and the mache unit of emanation... Taking Professor Mache's own value of 3.7 × 10⁻¹⁰ curie, the correct relationship is 1 milli-curie =..2.7 million mache units.

1923 R. Knox Radiogr. & Radiotherapeutics (ed. 2) ii. 513 This unit is so convenient that it is made use of at all the well-known spas (where the activity of the water is very low) and by many specialists of radium therapy upon the Continent, who all use the Maché [sic] unit for the dosage of emanation.

1930 J. B. Hoag Electron Physics ix. 122 One Mache unit is equal to 3.64 × 10⁻¹⁰ curies.

1926 R. W. Lawson tr. G. Hevesy & F. Paneth Man. Radioactivity xxiv. 178 One Mache unit is equal to 3.6 · 10⁻¹⁰ Curie per litre. The emanation content of strongly radioactive springs often amounts to several thousand Mache units.

1931 Rev. Mod. Physics 3 432 Mache Unit (M.E.) is a concentration unit referred to the Rn content of 1 liter of water or gas, etc. It is that quantity of Rn per liter which without decay products and with complete utilization of the α-particles can maintain by its ionization of air a saturation current of 10⁻³ e.s.u.

1971 S. Dresner Units of Measurem. 66 One mache is a concentration of 3.7 × 10⁻⁷ curie (Ci) of radioactive material in one cubic metre (m³) of a medium... Note: this unit is now obsolete.