The combustion tube with its charge is next placed in a furnace or chauffer of thin sheet iron (see middle figure above).
What is sold as Jena combustion tube should be preferred when this is the case.
This is a piece of combustion tube drawn out and narrowed at one end, as shown in fig. 76.
The combustion tube has attached in front a small V-Shaped tube charged with chromic acid, dissolved in 60 per cent.
The oxide of tin is placed in a porcelain boat (fig. 58), which is then introduced into a piece of combustion tube.
The combustion tube is heated by means of a Bunsen burner or alcohol lamp, L.
Wash out the combustion tube with some acid and add the washing to the contents of the beaker.
The lamp is then ignited and the flame introduced in the combustion tube D (Fig. 11).
Dry the filter, transfer the cleaned ore to a piece of combustion tube ten or twelve inches long and narrowed at one end.