Sorry if this question has a simple answer, but I've been unable to find it elsewhere.
Using a diffraction grating, burning ethanol (99.9%) will produce a rainbow of colours. However, when burning a mixture of alcohols (methanol 76.6%, ethanol 21.4%, propanol 0.3%) the rainbow pattern is missing. Could someone explain?
If methanol only emits a small range of wavelengths, why wouldn't there be a dimmer ethanol rainbow?