ART. 234 - On the Viscosity of Hydrogen as affected by Moisture

Summary

In Sir W. Crookes's important work upon the viscosity of gases the case of hydrogen was found to present peculiar difficulty. “With each improvement in purification and drying I have obtained a lower value for hydrogen, and have consequently diminished the number expressing the ratio of the viscosity of hydrogen to that of air. In 1876 I found the ratio to be 0·508. In 1877 I reduced this ratio to 0·462. Last year, with improved apparatus, I obtained the ratio 0·458, and I have now got it as low as 0·4439” (p. 425). The difficulty was attributed to moisture. Thus (p. 422): “After working at the subject for more than a year, it was discovered that the discrepancy arose from a trace of water obstinately held by the hydrogen—an impurity which behaved as I explain farther on in the case of air and water vapour.”

When occupied in 1888 with the density of hydrogen, I thought that viscosity might serve as a useful test of purity, and I set up an apparatus somewhat on the lines of Sir W. Crookes. A light mirror, 18 mm. in diameter, was hung by a fine fibre (of quartz I believe) about 60 cm. long. A small attached magnet gave the means of starting the vibrations whose subsidence was to be observed. The viscosity chamber was of glass, and carried tubes sealed to it above and below.