84 BENJ. PIKE'S, JR., DESCRIPTIVE CATALOGUE. 



the gas holders at any time. To use ; having filled the 

 gas-holders, the one with hydrogen and the other with oxy- 

 gen gas, fill the reservoirs on top nearly full of water, and 

 open the stop-cock that it may press on the gas ; turn the 

 stop-cock connected with the hydrogen gas holder, and set 

 the gas on fire as it issues from the jet ; the oxygen is then 

 slowly admitted, when the flame will be considerably reduc- 

 ed, and burn with a small blue light, and apparently to the 

 eye incapable of the astonishing effects which it produces, 

 as an iron wire will burn in its flame with the readiness of a 

 thread in a common candle. Procure a number of different 

 substances, as lime, chalk, pieces of pipe stem, clay, the 

 different metals, which may be about the size of half a pea, 

 and place them in a cavity in a piece of charcoal, and sub- 

 ject them to the action of the flame ; the lime will cause a 

 most intense light, insupportable to the naked eye. Plati- 

 num, which cannot be melted in any furnace, will be ivadily 

 fused and dissipate in vapor. Copper burns with a beau- 

 tiful blue flame. Cast-iron, with bright sparks ; and steel 

 wire, watch spring, with brilliant scintillations ; the calorific 

 effects are only surpassed by a powerful galvanic battery. 

 The gas holders are made of stout tin, handsomely japanned, 

 holding about ten gallons each, but may be made of cop- 

 per for about one half additional price, and larger size if 

 required. Price, in japanned tin, $15.00. 



" copper, $20.00. 



Compound Blow-Pipe, with Sliding Receivers. (Fig. 535, 

 next page.) This convenient arrangement of the compound 

 blow-pipe, may be understood by reference to the gasometer, 

 previously described (Fig. 533). The receivers as there 

 described, are suspended by cords passing over pulleys in 

 the top of the frame, and balanced by weights contained in 

 the upright tubes. The vessels are made of japanned tin, 

 or copper, of about fifteen gallons capacity ; the fixtures 

 are of brass; the whole mounted on a wooden base and 

 castors. 



Price, in japanned tin, - $30. 



" " " with flexible tubes and jet, $40. 



" in copper, - $40. 



' " " " $50. 



