the process can obtain full directions from any responsible dealer.
Limelight Jets.—These are of three general types, viz. the 'Blow-through,' the 'Mixed,' and the 'Injector.'
Of these the 'Blow-through' is now very little made, having been largely superseded by the 'Injector' pattern, but, as there are hundreds in common use in this country, they cannot yet be regarded as a thing of the past.
The exact design of this jet varies considerably, but all are alike in this, that a jet of coal gas is burned at the orifice of a more or less open nozzle, and a stream of oxygen blown through it on to a cylinder of lime which it thereby renders incandescent. Fig. 15 represents the various designs chiefly adopted for this jet, that marked A being perhaps the most usual, though C is also frequently met with.
In light-giving power there is not much to choose between the various types; probably D on the whole is the best in this respect, but so much depends upon the exact position of the two nozzles, and the smoothness or otherwise of that
provided for the oxygen blast, that exact comparisons are difficult.
'Blow-through' jets are the weakest form of limelight as used at the present day, and may be taken roughly as some 50 per cent. better than acetylene, or in other words, sufficient to illuminate a 12-foot picture at a distance of some 40 to 50 feet; but their advantage is, or was, that they only required one gas (oxygen) under pressure, the coal gas supply being obtained from the ordinary house main.
