The dual wavelength spectrophotometer, noted for its high sensitivity and accuracy in the recording of oxidation‐reduction and other reactions of membrane bound components in turbid suspensions of biological materials, has now been modified to scan the spectrum of these components over a reasonable wavelength range (40 nm) and in a short time (rates as rapid as 20 nm/sec). The baseline precision is not remarkable (approximately 1% error) but the method retains the intrinsic noise rejection properties of the dual wavelength technique. Two forms of the apparatus are discussed, one a simple modification involving a previously described time sharing compensating circuit, and the other incorporating a tapped potentiometer for more precisely correcting the baseline, and a comparator and error detector for correcting wavelength dependent sensitivity error.