K. DOMESTIC AND HOUSEHOLD ECONOMY. 491 



where heat without light is required as, for instance, for 

 gas stoves of whatever kind, or for boiling water and gener- 

 ating steam. When required to be used for lighting pur- 

 poses, this heating gas is made to bubble through a reservoir 

 containing rectified petroleum, of a specific gravity of about 

 0.68. It then passes at once into the pipes for circulation 

 and consumption, and issues from these burners a very excel- 

 lent gas, equal in illuminating power to sixteen and a half 

 candles, with a consumption of five cubic feet an hour in an 

 Argand burner. The experiments on the power of this gas 

 for both heating and lighting purposes are said to have been 

 thoroughly satisfactory, and the cost to be very much less 

 than that of coal gas, even when the price of coals is much 

 less than the very high rate which has prevailed in England 

 durino- the last six months. 



FLAME OF COMPRESSED GAS. 



According to a communication of F. Benavides, a jet of or- 

 dinary illuminating gas, issuing under pressure through a 

 sliglitly opened stop -cock, gives a flame of greater brill- 

 iancy than those of the street lamps, of only a few inches' 

 water pressure. When the cock is opened wider the veloc- 

 ity of efllux increases, air is carried along with the gas, the 

 combustion becomes more energetic, and the illumination 

 feebler, or disappearing entirely, while the temperature is 

 considerably elevated, as in the Buusen burner. If the press- 

 ure and velocity, as well as the amount of escaping gas, are 

 great, the flame only appears at a certain distance from the 

 orifice, the dimensions of the dark space between it and the 

 orifice being dependent on the pressure and the quantity 

 of escaping gas. Under a pressure of two atmospheres, 

 this distance is about one and a half inches, with a flame 

 about fifteen and a half inches in length, 1.2 inches wide at 

 the beginning, and about four inches wide at the end. The 

 temperature of the dark space is very low, as shown by the 

 slow rise of a thermometer placed in it ; probably due to ra- 

 diation from the flame. If a metallic wire is introduced into 

 the dark space, and brought in contact with the flame, and 

 then back into the dark space, the flame will follow it, and 

 the dark space may be obliterated, but will re-appear on re- 

 moval of the wire. A candle brought near to it, will show 



