9. Alterations to the service must not be made while the pipes are under pressure, but only after the main cock has been shut. 10. If portable apparatus, such as described in I., 12, are connected to the burners with rubber tube, the tube must be fortified with an internal or external spiral of wire. The tube must be fastened at both ends to the cocks with thread, copper wire, or with ring clamps. 11. The preparation, storage, and use of compressed or liquefied acetylene is forbidden. By compressed acetylene, however, is only to be understood gas compressed to a pressure exceeding one effective atmosphere. Acetylene compressed into porous matter, with or without acetone, is excepted from this prohibition. 12. In the case of plants serving 50 lights or less, not more than 100 kilos. of carbide in closed vessels may be kept in the apparatus house besides the drum actually in use. A fresh drum is not to be opened before the previous one has been two- thirds emptied. Opened drums must be closed with an iron watertight lid covering the entire top of the vessel. In the case of apparatus supplying over 500 lights, only one day's consumption of carbide must be kept in the generator house. In other respects the store of carbide for such installations is to be treated as a regular carbide store. 13. Carbide drums must not be opened with the aid of a flame or a red-hot iron instrument. 14. Acetylene apparatus must only be attended to by trustworthy and responsible persons. The rules issued by the AUSTRIAN GOVERNMENT in 1905 for the installation of acetylene plant and the use of acetylene are divided into general enactments relating to acetylene, and into special enactments in regard to the apparatus and installation. The general enactments state that: 1. The preparation and use of liquid acetylene is forbidden. 2. Gaseous acetylene, alone, in admixture, or in solution, must not be compressed above 2 atmospheres absolute except under special permission. 3. The storage of mixtures of acetylene with air or other gases containing or evolving free oxygen is forbidden. 4. A description of every private plant about to be installed must be submitted to the local authorities, who, according to its size and character, may give permission for it to be installed and brought into use either forthwith or after special inspection. Important alterations to existing plant must be similarly notified. 5. The firms and fitters undertaking the installation of acetylene plant must be licensed. The special enactments fall under four headings, viz., (_a_) apparatus; (_b_) plant houses; (_c_) pipes; (_d_) residues. In regard to apparatus it is enacted that: 1. The type of apparatus to be employed must be one which has been approved by one of certain public authorities in the country.