The Art of projection and complete magic lantern ... - Yesterday Image

—66it will soon force the air out, apply a match, of course holding the tinaway from the body. If mixed the gas goes off with a small report, ifthe oxygen is pure nothing will happen, nor will it light, if the match isdropped into the tin it will only burn with increased brilliancy, until allthe oxygen is exhausted.Oxygen and hydrogen gases by themselves are as safe as theword safety implies. Fill a jar or bottle with hydrogen and dropa lighted match inresult, the match is immediately extinguished :hydrogen will not burn of itself, it must have oxygen to support it, butallow the hydrogen to escape in a stream, and on reaching the air it willhght and burn, as our common house gas lighted at itsburner illustrates,because the oxygen in the air supports it, causing combustion, withoutthe aid of oxygen, hydrogen is as harmless an illuminant as is possibleto imagine.For oxygen, take a jar or vessel filled with this gas in the samemanner, plunge the match or taper into the vessel, and the match willburn wnth increased brilliancy, the gas itself will not light, that isimpossible. Oxygen alone is a supporter of combustion, and if allowedto escape into a room in any quantity is perfectly harmless, in fact in acrowded room its results are beneficial. The reader may say, if thesegases are harmless, how is it that gas bags and even cylinders haveexploded. If the true facts could only be traced, it would be proved inevery individual case that the accident was caused by the gases oxygen andhydrogen being mixed, and a light applied,— no accident or explosion canpossibly occur unless this is done, even if the gases are so mixed it isperfectly safe until a light is applied. We were once in a theatre, when agas bag exploded on the stage, causing nothing more than a loud report,the manager appeared and explained to the audience, that a gas bag hadbeen filled too full and consequently burst, this the audience from theirapplause, evidently thought was a sufficient explanation. The real factwhich we learnt afterwards was this : the man who was paid is. 6d. to2S. a night to work the limelight was 7ion coviptis /nentus, and had filledup a half-full oxygen bag with hydrogen, and, in attempting to lightthe jet, he was thrown several feet away. The time may come whenevery accident of this kind will be investigated by a qualified board, andthe culprit punished, the sooner the better for all.If gas bags are used, each bag should be marked with a large H or Oboth sides, and under no consideration should they be used forbut those marked.any gasSafety Valves.— Valves fitted with pumice and back pressure