This gas has been introduced under the name of the inventor, Blau.

It is liquefied illuminating gas produced by distillation of mineral oils in red-hot retorts. Chemically the gas consists of the same elements as ordinary coal gas, but in essentially different proportions. Blau gas is, however, free from carbon oxide, and has therefore the advantage over coal gas of not being poisonous.

The analyses give the following compositions of the Blau gas: -

One litre gas (1.246 gr.) contains, at 0° C. and 760 m.m. barometer pressure,

1.042 gr. carbon. 0.204 gr. hydrogen. From the absolute weight (1.246 gr.) of one litre the specific weight of the gas is found to be 0.963.

The number of calorics was found to be 12,318 per one kg., or 15,349 per one cubic metre.

By comparison of equal volumes of various gases in respect of heat and light the following results are obtained: -

The Blau gas can, like all active gases, be compressed and liquefied, and in this latter condition it occupies 1/400 part of its gaseous volume. It is collected in the ordinary steel cylinders for transport, the smallest cylinder taking 0.49 litre or 0.25 kg., and the largest 49 litres or 25 kg. of liquid Blau gas under a pressure of 100 atmospheres.

The Blau gas, being very inert, is therefore difficult to bring to explosion. Its extent of explosion embraces only 4 per cent. (from the mixing proportions of 4 per cent. of gas and 96 per cent. of air up to 8 per cent. of gas and 92 per cent. of air), while that of coal gas is 13 per cent. (from the proportions of 6 1/3 per cent. of gas and 93 2/3 per cent. of air up to 19 1/3 per cent. of gas and 80§ per cent. of air), and that of acetylene 47 per cent. (from 2 per cent. of gas and 98 per cent. of air up to 49 per cent. of gas and 51 per cent. of air).