For the substances dealt with in this paper I have been indebted at various times, to the kindness of Mr David Hooper, Quinologist to the Madras Government. The observations have been made with several instruments, but have all been reduced to the scale of the direct vision spectroscope of the Chemical Laboratory of the Edinburgh University, kindly placed at my disposal for the most important part of the work. The illumination used with this instrument is a 10-candle power incandescent lamp; with the other instruments sun-light was used. I have thought it better for practical purposes to draw the spectra to the natural scale of the instrument than to reduce them to a scale of wave-lengths, but data are supplied for finding the wave-length corresponding to any part of the spectrum. To represent the varying shades of an absorption spectrum is extremely difficult, and the results usually obtained are, at best, far from satisfactory. The method I have employed is to draw the spectra on a large scale, shading the various parts by aid of a light curve, and then reduce this drawing to the required size by photography. The result, though not all that could be desired, is fairly satisfactory.