The rapid analysis of glass is made possible by replacing the crucibles in which time-consuming fusion is carried out by a device for quantitative acid dissolution under pressure and subsequent atomic-absorption spectroscopic determinations of the elements.The sample is decomposed by hydrofluoric acid at 105 °C in a decomposition vessel consisting of a crucible-shaped stainless-steel container fitted with a removable PTFE crucible and a stainless-steel screw-cap with a PTFE disc inserted in the metal body. Subsequent addition of boric acid forms the analysis matrix of fluoroboric acid-boric acid for the atomic-absorption determinations of silica, alumina, iron, titanium, magnesium, calcium, sodium and potassium.This procedure obviates the use of platinum vessels, prevents losses of constituents due to alloying, reduction and volatilisation, does not introduce extraneous cations, and is reliable, simple and rapid to perform.