A blast furnace with a blowpipe (12) opening through the furnace wall (11), has apparatus for analysis (20) in a raceway (18) adjacent the blowpipe opening in a bed of the blast furnace. The apparatus includes means (24) arranged in relation to the blast furnace to transmit an optical signal into the raceway, and means (30) for monitoring a received signal derived from reflection or scattering of the transmitted optical signal in the raceway. Means (32) is provided to analyse the received signal in relation to the transmitted signal and to thereby obtain a measure of a parameter of the raceway. The method of analysis comprises transmitting an optical signal into the raceway, monitoring a received signal derived from reflection or scattering of the transmitted optical signal in the raceway, and analyzing the received signal in relation to the transmitted signal to obtain a measure of a parameter of the raceway.