A photoelectric apparatus is described which was designed for routine assays of vit. A by SbCl3. Meticulate directions are given for the prepn. of unsaponifiable samples and for their estimation. One method of calculation requires a sample of the vit. concentrate used in the manufacture of margarine. When this is not available the fading technique is recommended, in which the non-specific absorption is allowed for by the absorption after 30 min. when the SbCl3-vit. A blue has declined by 90%.