The Bakeria/i Lecture. 



1821.) 



from moist charcoal contains the same 

 elements, with carbonic oxide and car- 

 bonic acid ; and that no other definite 

 compound of carbon and hydrogen can 

 be recognised in them, except oietiant 

 gas. 



Comparative experiments on the illnmi- 

 natiny and henting powers of olefiant, 

 coal, and oil gases, and on some gene- 

 ral properties of radiant matter. 

 In the following experiments I em- 

 ployed a gasometer with coimterpoise 

 weights acting over regulating pullies, 

 and capable of containing about .WOO 

 cubical inches, or about 2,89 cubical 

 feet : the different jets were attached f o 

 it in the usual way, and the pressure 

 was measured by the difference in (he 

 level of the water within and witliout 

 the bell, to which was attached an 

 accurately graduated scale sliding 

 through the frame of support. 



Having filled the gasometer with pure 

 olefiant gas, it was allowed to issue 

 from a brass jet having a single perfora- 

 tion of ji of an inch diameter, under a 

 pressure ofa half inch column of water; 

 it was then inflamed, and regulated by 

 means of a stop-cock, so as to produce a 

 light equal to that of a wax candle 

 burning with full brilliancy ; the rela- 

 tive intensity of the light of these flames 

 was ascertained by a comparison of 

 shadows. Under these circumstances, 

 the consumption of gas was found = 640 

 cubical inches per hour, or 0,37 cubical 

 feet. When the same burner was used 

 with oil gas, it consumed 800 cubical 

 inches per hour, or = 0,47 cubical feet. 

 I now employed an Argaud burner, 

 with a cylindrical glass, constructed in 

 the usual way, with 12 holes each of the 

 same dimensions as that of the single 

 jet, and forming a circle 0,7 inch dia- 

 meter. The jiresNure being 0,5 inch, 

 the flame was so regulated as to burn 

 witii its full intensity without producing 

 smoke, and its liglit being measured by 

 a comparison of sliadows, it was found 

 equal to ten wax candles. The con- 

 sumption of gas amounted to 2600 cu- 

 liical inches, or about a cubical foot and 

 a half per hour. 



If the result of this experiment be 

 compared with the above,in which a sin- 

 gle jet was used, it will appear that the 

 proportion of light from a given quan- 

 tity of gas is increascfl in a very higii 

 ratio by emj)loying many flames near 

 each other, the consumption of the 

 single jet giving a light of one candle, 

 being = 640 cubical inche>». whereas 



157 



the Argand burner gave a light of ten 

 candles, with the consumption not ot 

 640 X 10 cubical inches, but of 260O 

 cubical inches. It will be remembered, 

 that in the latter the combustion is per- 

 fected by a central current of air, ren- 

 dered more rapid by the glass tube 

 which surrounds the flame. Count 

 Rumford showed some time ago, " that 

 the quantity of light emitted by a given 

 portion of inflammable matter in com- 

 bustion, is proportional to some high 

 ratio to the elevation of temperature, 

 and that a lamp having many wicks 

 very near each other, so as to commu- 

 nicate heat, burns with infinitely more 

 brilliancy than the Argand lamps in 

 common use." The construction of 

 the gas Argand burner is particularly 

 calculated to produce an effect of 

 this kind ; and to such a cause the 

 great increase of ligiit relative to the 

 consumption of gas may probably be 

 attributed. 



The gasometer being filled with oil- 

 gas, an Argand burner, giving the light 

 of eight wax candles, was found to con- 

 sume 3900 cubical inches per hour; 

 and the same intensity of light was 

 produced by the same quantity of arti- 

 ficial oil gas; that is, of a mixtuie of 

 three parts of olefiant and one of hy- 

 drogen. 



The apertures of burners for coal-gas 

 require to be considerably larger than 

 those for olefiant or oil-gas. In the 

 burner employed in tlie following ex- 

 periments, each hole was /j inch dia- 

 meter, and the circle upon the circum- 

 ference of whic'i they were placed, was 

 0,9 inch diameter. The light of the 

 flame was found equal to five wax Ccan- 

 dles only, and the ccmsumpfion of gas 

 per hour amounted to 6560 cubical 

 inches. 



With a mi'ciure of six parts by mea- 

 sure of hydrogen with five of olefiant 

 gi'.s, the light of the flame was some- 

 what more intense; and the quantity 

 of gas consumed by the same burner, so 

 adjusted as not to smoke, was 600O 

 cubical inches. 



It appears from the above data, that 

 to produce tlie light of ten wax candles 

 for one hour, there will be required, 

 2600 cubical inches of olefiant gas. 

 4875 ... oil-gas 

 131 20 - - . coal-gas; 



and that the quantity of oxygen con- 

 sumed 



by the olefiaHt gas will be = 7800 cub. in, 



liy the oil-gas - =11.578. 



by the cnai-gns - =8l5I(i. 



Olefiant 



