Abstract: A metal vapor discharge lamp includes an arc tube having on an inner surface a coating of multi-layer construction including a layer preferably facing the interior discharge space of the arc tube and formed with a strongly covalent bonded material and at least another layer made to have a function of shielding water, whereby reaction of enclosed materials with the arc tube and oozing of water from the arc tube can be prevented, and cracking and peeling of the coating can be effectively prevented from occurring.

Abstract: A carbonate spring bath system creates a bath water dissolved with CO.sub.2 gas and supplies the same to a bathtub. The system includes a source of a concentrated CO.sub.2 gas, a circulation path connected to the bathtub and including a booster pump for circulating a bath water from and into the bathtub. CO.sub.2 gas and air supply lines are connected to the circulation path upstream of the pump. The CO.sub.2 gas and air supply lines includes valves which are opened and closed to provide the CO.sub.2 gas and the air at a suitable mixture ratio such that the CO.sub.2 gas and air are forced to dissolve in the pressurized bath water. Disposed downstream of the pump is an accumulator for separating undissolved gas in the bath water and storing in a gas chamber the undissolved gas emanating from the bath water. A recycle line connects the gas chamber to the circulation path upstream of the pump to return the undissolved gas to the circulation path.

Abstract: An electrochemical gas sensor comprises an insulating substrate, active and counter electrodes disposed on a surface of the insulating substrate mutually spaced to have respectively reactive portions, a reference electrode spaced from the active and counter electrodes and having a reactive portion, and a solid electrolyte layer formed to cover the reactive portions of the active, counter and reference electrodes, whereby the sensitivity to gases of the active electrode is improved and stabilized.

Abstract: A gas detector for detecting the leak of fuel gases, such as hydrogen gas, methane gas, butane gas, with improved reliability in detecting the gas leak. Said gas detector includes a main gas sensing element showing the change in resistance to target gases, such as methane, butane, hydrogen, as well as to non-target gases, such as alcohol, steam, smoke; an auxiliary gas sensing element showing change in resistance rather to non-target gas than to target gas; the first comparator receiving the output induced by resistance change in main gas sensor, as input; the second comparator with reference voltage set at lower level than that for the first comparator; and a gate circuit for blocking the alarm driving signal of the second comparator by the output induced by resistance change in auxiliary gas sensor. The output obtained from either said gate circuit or the first comparator is used for alarm driving signal of alarm circuit.

Abstract: A gas detector comprising a main gas sensing element showing the resistance change to both the detection target gases, such as methane, butane, hydrogen gases, and non-target gases such as alcohol steam, smoke; an auxiliary gas sensing element showing the resistance change primarily to non-target gases along; the first comparator to which the output based on the resistance change of main gas sensing element is received as input in parallel form; the second comparator with lower reference electric power than that of the first comparator; a gate circuit to cut off the alarm actuating signal from the second comparator by means of output induced by the resistance change of auxiliary gas sensing element. Either the output from said gate circuit or the output from said first comparator is used for alarm actuating signal of alarm circuit.