COMPOUNDS OF CAKBON WITH OXYGEN AND NITKOGEN 397 



'incandescent charcoal , the air first burns the carbon into carbonic 

 anhydride, but this in penetrating through the red-hot charcoal is 

 transformed into carbonic oxide, C0 2 -f C = 2CO. By this reaction 

 carbonic oxide is prepared by passing carbonic anhydride through char- 

 coal at a red heat. It may be separated from the excess of' carbonic 

 anhydride by passing it through- a solution of alkali, which does not 

 absorb carbonic oxide. This reduction of carbonic anhydride explains 

 why carbonic oxid6 is formed in ordinary clear fires, where the incoming 

 air passes over a large surface of heated coal. A blue flame is then 

 observed burning above the coal ; this is the burning carbonic oxide. 

 When charcoal is burnt in stacks, or when a thick layer of coal if 

 burning in a brazier, and under many similar circumstances, carbonic 

 oxide is also formed. In metallurgical processes, for instance when 

 iron is smelted from the ore, very often the same process of conversion 

 of carbonic anhydride into carbonic oxide occurs, especially if the 

 combustion of the coal be effected in high, so-called blast, furnaces and 

 ovens, where the air enters at the lower part and. is compelled to pass 

 through a thick layer of incandescent coal. In this way, also, com 

 bustion with flame may be obtained from those kinds of fuel which 

 under ordinary conditions burn without flame : for instance, anthracite, 

 coke, charcoal. Heating by means 

 of a gas-producer that is, an 

 apparatus producing combustible 

 carbonic oxide from fuel is 

 carried on in the same manner. 19 

 In transforming one part of char- 



19 In gas-producers all carbonaceous 

 fuels are transformed into inflammable 

 gas. In those which (on account of their 

 slight density and large amount of water s 

 or incombustible admixtures which ab- 

 sorb heat) are not as capable of giving a 

 high temperature in ordinary furnaces 

 for instance, fir cones, peat, the lower 

 kinds of coal, &c. the same gas is ob- 

 tained as with the best kinds of coal, 

 because the water condenses on cooling, 

 and the ashes and earthy matter remain 

 in the gas-producer. The construction 

 of a gas-producer is seen from the ac- 

 companying drawing. The fuel lies on 



the fire-bars O, the air enters through Fl ^ 63 ._ Ga , producer for the formation of carbon 

 their and the ash-hole (drawn by the monoxide for heating purposes, 



draught of the chimney of the stove where 



the gas burns, or else forced by a blowing apparatus), the quantity of au % being exactly 

 regulated by means of valves. The gasas formed are then led by thejube V, provided 



