174 PROFESSOR WARTMANN ON DALTONISM, 
placed close to it*. The flower of the rose seems to him greenish- 
blue, and he calls the ash-colour of the quick-lime (chauz vive) 
of commerce light green +. 
I presented to him successively papers shaded with different 
tints, requesting him to assort those which appeared to him 
similar. I instantly perceived that the influence of the surface 
more or less glossy of the paper, and the glare which results 
from this, prevented his stating with certainty, and I gave up 
this mode of experiments, in which the judgements of the sight 
were in a manner modified by those of the touch{. 
I wished to know what effect the sight of a solar spectrum 
would produce on him. I operated by means of a good prism, 
in very favourable weather and in a dark chamber, on the 7th of 
May 1839, between 9 and 10 o’clock in the morning. The co- 
loured bands received on a screen of white paper were brilliant 
and distinct ; they extended a length of about 0":102. D#*** 
perceived four colours only, the blue, green, yellow and red. 
He limited the blue part exactly to the space occupied by the 
violet, indigo and blue; he called the green and yellow bands 
less an interval of 0™-0U2 towards the orange, green; he called 
that band of 0™002 and a fraction of the red 0™:012 in breadth, 
yellow; lastly, the remaining 0™-008 of red appeared to him of 
a red difficult to define, although certainly a red§. 
These anomalies in the perception of reflected colours once 
known, it remained to verify them for refracted light. I em- 
ployed, for this purpose, thirty-seven plates of glass differently 
coloured, and I wrote down, from the dictation of the daltonian, 
the different impressions which he experienced on placing each 
of them in succession between the sky and his eye. I repeated 
these trials several times, in order not to leave the results ques- 
* I have observed a like circumstance in another daltonian, M. Mary of 
Metz. He could not perceive a young peasant girl clothed entirely in red, 
and who crossed a meadow, the green colour of which had taken the deep tint 
which is common some instants after sunset. 
+ Professor M * * * of Zurich is similarly cireumstanced, &c. 
} I have remarked, like M. Seebeck, that the judgement passed by daltonians 
on colours is less positive and less exact for opake media than for transparent 
substances. 
§ I have already said that many dichromatic daltonians see better in a demi- 
obscurity than other persons whose sight is more piercing by day than theirs ; 
the same is the case with D * * *, and two other persons whom I examined. 
Does not this proceed, as M. Seebeck presumes (Mem. cit., p. 224), from the 
fact that the less refrangible rays being the first to disappear in twilight, the 
diminution of the glare of light is more sensible to ordinary eyes, which perceive 
these rays better than they? 
