On Laboratory Arts

On Laboratory Arts is a book by Richard Threlfall, Professor of Physics in the University of Sydney. The contents list hints on the manipulation of glass and on glass-blowing for laboratory purposes. One section on testing glass says to reject glass which has lumps or knots, is obviously conical, or has long drawn-out bubbles running through the substance.

On sizes, the text says that for general purposes tubes about one-quarter inch in inside diameter, and from one-twentieth to one-fortieth of an inch thick, are most in demand. The text quotes advice that the two lenses of an objective may be readily separated by setting it on edge, and tells of a 7-inch objective made by Mr. Clark that was brought to be cleaned. On gold-plating, the text says a current density of say ten to fifteen amperes per square foot may be used, that keeping the electrodes moving or the solution stirred is a considerable advantage, and that depositing may go on for about three minutes.