This simple and convenient apparatus has been specially designed to meet the requirements of refiners and foundrymen for nitrogen degassing. Although porosity in castings can be avoided if sufficient care and skill is used in the melting and casting operations there still remains a possibility of rejections due to gas. Flushing the molten metal with nitrogen is a simple and cheap way of ensuring that the melt is gas free and can be regarded as a complete insurance against gas porosity. Degassing with nitrogen is a purely physical process. It has no effect on the composition of the metal, neither does the gas attack the crucible. Metal losses are not incurred, in fact, as the metal is de-gassed before casting, it is possible to melt copper alloys under a charcoal cover so as to reduce metal losses. In the case of aluminium alloys, a flux cover should be used when degassing. Another important advantage of using nitrogen is that metallurgical control of the degassing operation is unnecessary. It is impossible to “over degas”, in fact, a large excess of nitrogen can be passed through the melt without causing any harm. The apparatus required is simple and inexpensive and the cost per tonne of metal processed is extremely low.