306 Scientific Proceedings, Royal Dublin Society. 
Members of the Society are well aware that what is technically 
known as “ water-gas”’ is produced by passing steam over red-hot 
coke when the following change is realised :— 
H,O + C =CO+ H.,. 
That is to say, the carbon in the form of coke, when sufficiently 
heated, removes the oxygen from water vapour, and produces there- 
with carbon monoxide gas, while hydrogen is also set free. The 
mixture of combustible gases so obtained gives a very slightly 
luminous flame and has little odour. When petroleum or other 
oils are vaporised at a sufficiently high temperature in this gas, 
their products render the flame much more luminous and com- 
municate a strong odour. The product is “ carburetted water-gas,”’ 
and contains about 30 per cent. of carbon monoxide, the rest 
consisting of hydrogen and small proportions of its carbides. 
This gas is much cheaper than coal-gas ; it is more readily and 
quickly manufactured, and its production enables a gas company 
to use up a considerable proportion of its coke to advantage. 
Moreover, it can be easily made of almost any desired illuminating 
power, and is not more explosive with air than plain coal-gas. It 
is therefore much to the interest of a gas company to mix a 
considerable proportion of this water-gas in their supply, and 
such mixtures have been used in the United States since 1878, 
and to a much smaller extent in these countries since 1891. Some 
American cities such as Boston, New York, and Chicago now use 
almost unmixed water-gas; but in the United Kingdom compara- 
tively few towns as yet use a mixture, and in those which do, 
50 per cent. of water-gas is seldom added. In London very little 
has hitherto been used, and several companies are said not to have 
distributed any. There does not seem to be any statutory difficulty 
in the way of the companies substituting water-gas for coal-gas, 
and there would not be any general objection to their doing so 
wholly, provided there was no greater risk to health and life than 
with ordinary coal-gas. But that such danger does exist is beyond 
question, as carbon monoxide gas is a powerful and direct poison. 
A gaseous mixture which contains much of it, as Dublin gas now 
does, is necessarily more poisonous than the ordinary coal-gas 
which seldom included more than 6 per cent. Therefore, in the 
lecture already referred to, I said just so much by way of warning, 
