354: 
well-marked spectrum, and in this respect Aphideine is little, 
if at all, less remarkable. On very gradually adding a small 
quantity of hypochlorite of soda to a recently prepared solu- 
tion, the original spectrum No. 1 is changed to that shown 
in No. 3; but the compound then formed changes quickly 
into another, the spectrum of which shows two similar narrow 
absorption-bands, somewhat nearer the red end, not removed 
by the addition of ammonia or citric acid, disappearing at 
once when the ferrous salt is added to an alkaline solution, 
and partially restored by reoxidisation, if not kept long ina 
deoxidised state. The same results may be obtained by using 
the Aphideine extracted cold by crushing the insects in a 
small quantity of water, but this solution, which is often 
turbid, changes so rapidly on exposure to the air, that it is 
difficult to examine it before it has been considerably altered. 
On crushing the living insects in a watch-glass with a little 
water, the solution is at first pink, but rapidly becomes 
orange. On pouring this off into another watch-glass, leaving 
it for a short time, and then pouring the comparatively clear 
solution into an experiment cell, it will be found that the 
original Aphideine has been completely altered. On adding 
a little ammonia, instead of the spectrum showing a broad, 
continuous band like No. 1, three well-marked narrow bands 
are seen,as shown by No.2. For the actual position of these 
and those in other spectra, I refer to the table given at the 
end of this paper. 
The relative intensity of these three bands varies con- 
siderably, and this led me to conclude that two different 
substances were present, as was subsequently proved in the 
manner deseribed in the sequel. A weak acid entirely re- 
moves the narrower band nearest the red end, raises the 
others somewhat, and develops a new band still nearer the 
extreme blue, which can only be seen with excellent sun- 
light. On adding the ferrous salt to the alkaline solution, 
the absorption-bands gradually vanish, and, if kept deoxidised 
for some time, a new compound is formed with an absorption- 
band between the orange and yellow, and another in the 
green, disappearing when reoxidised. On the contrary, if the 
solution which gives the spectrum No. 2 be kept for a while 
exposed to the air, it is gradually changed into another com- 
pound, giving the two absorption-bands shown in No. 3. On 
keeping still longer these disappear, and the spectrum shows 
only a general absorption extending over the blue and green 
without any narrow bands. [am therefore inclined to believe 
that the compounds which give spectrum No. 2 are gradually 
altered into two other substances, which when mixed give 
