362 
tion. I am much inclined to adopt the latter explanation, 
for if citric acid be added to an aqueous solution of the fresh 
colour, and then a small quantity of hypochlorite of soda, the 
colour is changed from pink to pink-red, the absorption is 
found to extend more towards the red end, and to be more 
uniform over the green and blue ; in all which particulars it 
corresponds with the spectrum of new wine. No such change 
occurs when the wine is treated in the same manner, as 
though this alteration had already taken place. Both these 
colours belong to my group B ; but when either is still 
further oxidized by means of rather more hypochlorite of 
soda, a sort of orange colour is produced, which seems to 
correspond with that of port-wine kept for twenty years or 
more in the cask ; and Avhen still further changed, it 
becomes quite pale, like very old wines. The following table 
Avill sIioav these facts more clearly : 
Colour of dark grapes in citric acid and water, 4 •• 4| -- 8| 11 -- 
Ditto, after adding a little hypochlorite of soda, 3^ •• 3-f 
New natural port wine . . . . . 3^ •• 3f 
Ditto, after adding a little hypochlorate of soda, 31 •• 3f 
Colour of dark grapes with more hypochlorite 
of soda . 5-6 — 10 — 
New natural port wine with ditto . . .5-6 — 10 — 
1831 port from the cask . . . . 5 •• G — 10 — 
Since this change in the spectrum depending on the state 
of oxidization is of considerable interest as illustrating a gene- 
ral laAV, I here subjoin a Avoodcut, in order to render my mean- 
ing more intelligible to those not accustomed to the use of 
the symbols employed in the above table. Fig. 1 shows the 
spectrum of the colour of dark grapes in its natural state, in 
citric acid and Avater. Fig. 2 is the spectrum of the oxidized 
modification met with in neAv Avines ; and fig. 3 that of the 
FIC.I 
FIG, 2 
FIG.3 
per-oxidized colour found in very old Avines, or formed by the 
more complete artificial oxidization of the other tAvo. 
