Cronstedt placed a bulb in the centre of his blowpipe.
The simplest and oldest form of blowpipe is a conical brass tube, about 7 in.
It fuses easily in the electric arc. It oxidizes superficially when heated, but fairly rapidly when ignited in an oxidizing blowpipe flame, forming a black smoke of the oxide.
The introduction of the blowpipe into dry qualitative analysis by Axel Fredrik Cronstedt marks an important innovation.
It is infusible before the gas blowpipe, but in the oxyhydrogen flame fuses to a clear colourless glass, which has a hardness of 5 and specific gravity 2.2.