SOIOPTirON MANUAL. 187 



contrivances to lessen its drawbacks. Gas holders, as 

 described in the last article, cannot, of course, be carried 

 from place to place. In bags, there is considerable bulk, 

 and a necessity for weights and pressure boards. Cylinders 

 are heavy, and the pressure which, has a thousand times the 

 force needed has to be risked, retained and regulated. 

 These disadvantages might be obviated, it is thought by 

 some, by the simultaneous production and consumption of 

 the gases. 



A copper hydrogen generator, about thirty inches high, 

 similar in shape to Fig. 51, but with the zinc suspended so 

 as to sink into the acidulated water, to keep up the supply 

 of the disengaged hydrogen as it becomes expended, has 

 been in market for many years ; but its being abandoned 

 by those who have used it is not very assuring. 



A good light is produced by vapor from heated gasoline, 

 or other hydrocarbons, pressing into the mixed blowpipe, 

 but it can hardly be as safe as a jet of oxygen through an 

 ordinary alcohol flame. 



At this very time there is much said in favor of generating 

 oxygen at just the rate required by the jet, by gradually 

 feeding the oxygen material to the melting apparatus. We 

 are now waiting to see this process develop into complete 

 success, but the question arises as to whether the additional 

 care of generating the gases while running the light will 

 not prove too much for ordinary faculties, and result in 

 the proverbial experience occasioned by having too many 

 irons in the fire at once. 



The gases, with the use of cylinders, into which they are 

 compressed by pumping, are furnished by dealers at about 

 20 cents a foot for oxygen, and 3 cents a foot for city gas. 

 Many exhibitors in the vicinity of large towns are thus 

 supplied. 



