The beta activities of K42, P32, and As 76 were examined for small order effects with a thin lens and an intermediate image spectrometer. The linearity of the spectrometers was checked by examining the unique beta spectrum of Y90;The 12:4-hour activity of K42 was found to have 2 beta groups with energies of 1.985 +/- 0.015 Mev and 3.545 +/- 0.010 Mev. The 3.54 Mev beta group was found to be a first forbidden transition with a spin change of 2 from its shape and log ft (Wo2 - 1) value. The 1.985 Mev transition was found to have essentially an allowed shape and apparently corresponds to a first forbidden transition with a zero spin change. Its allowed shape indicates that the nuclear parameters Z 3 or Y1 (7) must have values greater than 10. The possible admixture from the C2 1 term (7) is less than 10 percent. What appeared to be a very weak third beta group of 0.4 or 0.5 Mev was also found. (Abstract shortened by UMI.)