converting them into the respective phosphates, and these bodies are less refractory. A mantle exposed to the combustion products of crude acetylene soon becomes brittle and begins to fall to pieces, occasionally showing a yellowish colour when cold. The actual advantage of burning acetylene on the incandescent system is not yet thoroughly established-- in this country at all events; but it is clear that the process will not exhibit any economy (rather the reverse) unless the plant is provided with most capable chemical purifiers. Phosphorus, sulphur, and ammonia are not objectionable in crude acetylene because they confer upon the gas a nauseous odour. From a well-constructed installation no acetylene escapes unconsumed: the gas remains wholly within the pipes until it is burnt, and whatever odour it may have fails to reach the human nostrils. A house properly piped for acetylene will be no more conspicuous by its odour than a house properly piped for coal-gas. On the contrary, the fact that the carbide impurities of acetylene, which, in the absolutely pure state, is a gas of somewhat faint, hardly disagreeable, odour, do confer upon that gas a persistent and unpleasant smell, is distinctly advantageous; for, owing to that odour, a leak in the pipes, an unclosed tap, or a fault in the generating plant is instantly brought to the consumer's attention. A gas wholly devoid of odour would be extremely dangerous in a house, and would have to be scented, as is done in the case of non-carburetted water-gas when it is required for domestic purposes.