NATURAL PHILOSOPHY. 177 



and the shape and size and position of the chimney have much more 

 influence in effecting perlcct combustion than the chimney of a ga:<- 

 ilame. The difficulty of attaining a correct indication of the ilhimin- 

 aiing power of gas by comparison with other llames points to the 

 adoption of the atmospheric test, invented by Professor Erdmann. 

 By that instrument, neither photometers, nor candles, nor blackened 

 chambers are required, the illuminating power of the gas being deter- 

 mined by the quantity of atmospheric air mixed with a given quantity 

 of gas before it ceases to give white light. Such a simple method of 

 testing the illuminating power of gas lias peculiar claims to favor at 

 the present time, as the difficulty of attaining accurate results by plio- 

 tometrical observations has been shoAvn by the Birmingham experi- 

 ments to be. even greater than before supposed." 



Increasing the Illuminating Power of Gas. The editor of the San- 

 it ;!!!/ Reporter (England), in an article on testing gas, says: " The 

 following are distinct modes of increasing the power of an argand 

 burner consuming ordinary coal-gas: 1. Contracting the central 

 opening to about "45 to "5 of an inch diameter. 2. By a perforated 

 disc round the burner, and resting on the gallery which supports the 

 burner, o. By interposing a thin piece of paper or nietal to con- 

 tract the passage of air through the central opening. 4. By placing 

 a little contracted cap on the top of the chimney. Now, every one 

 of tiiese contrivances will considerably increase the power of the 

 argand burner. Moreover, all these contrivances act on the simple 

 principle of diminishing the velocity of the current of atmospheric air, 

 and thus allowing the minute particles of carbon, which the gas con- 

 tains, to be longer suspended in the ilame." 



OX THE CHEMICAL AND PHOTO METRICAL TESTING OF ILLUM- 

 INATING GAS. 



At the last meeting of the British Association, Prof. "VV. B. Rogers 

 of Boston, described the instruments and methods which have been 

 lately adopted in the gas inspection organized by law in the State of 

 Massachusetts, comprising the measurement as well as testing of gas. 

 Connected with the former of these objects, an account was given 

 of the adjustments of the standard measure for gauging gasholders, 

 of a universal clamp for meter-connections, and of an appendage 

 combining a delicate thermometer and pressure-gauge for the inlet 

 and outlet of the meter, and by which the rate of delivery is accu- 

 rately adjusted. For chemical testing, the eudiometer, consisting 

 of Ti graduated tube, with cylindrical enlargement, is permanently 

 inclosed in a wider tube full of water, which maintains the temperature 

 nearly uniform. The mouth of the graduated tube is furnished with 

 a hollow ground stopper, for holding the several liquid absorbents 

 used in the successive experiments. With this apparatus it is easy 

 to determine the percentage of carbonic acid, of illuminating hydro- 

 carbons, of oxygen, and of carbonic oxyde ; after which the hydrogen 

 and light carbureted hydrogen are ascertained by explosion, by 

 means of an instrument consisting mainly of two glass tubes, united 

 below by a long loop of rubber-tube, being a modification of Frank- 

 land's apparatus. For determining the sulphur, an improved arrange- 

 ment is used, in which the stream of water supplying the Liebig's 



