374 
(luce no change in weak acid solutions ; but when added to 
the solution in sulphuric acid they alter it into a deep red 
colour, changed into an orange-yellow by excess. Deoxidizing 
reagents, such as hyposulphite of soda, restore the deep red to 
the original yellow. The most useful test in connection with 
the various other colours already described is hypochlorite of 
soda gradually added to the solution in sulphuric acid. This 
first makes it a deep red, giving the spectrum 3 . . 4 , 
and the addition of a little more produces scarcely any further 
change ; but when large excess has been added it fades to an 
orange, giving the spectrum 6.-7 — . The colouring matter of 
fresh wort treated in the same manner is not turned at all 
red, and though the colour of finished beer is changed to red 
in a very similar manner, yet, after so much hypochlorite has 
been added as to turn it deep pink-red, a very little more 
makes it pale yellow. We may take advantage of this circum- 
stance to detect calumba root. 
In examining any suspected beer, it, and a similar quantity 
of genuine, should be evaporated in separate dishes, so that 
the results may be more accurately compared. The presence of 
calumba root is first somewhat betrayed by the fact of the 
resin which separates on evaporation being abnormally yellow, 
and when the syrup is dissolved in alcohol, and the solution 
evaporated to dryness, the purified colour is decidedly brighter 
yellow than it ought to be. Taking then two experiment 
cells, so much of the colour of the genuine beer should be 
dissolved in one — in sulphuric acid — as to give a decided 
orange yellow, with a spectrum 5 . . 6 - - 7 — ; and in the other 
cell so much of the suspected material as to give a colour of 
about the same tint. In both cases about one fourth of the 
bulk of the liquid should be alcohol, so as to prevent the for- 
mation of any precipitate. Hypochlorite of soda should then 
be added very gradually, and in equal quantities to both, 
when at first both will change to red, having a pinker tint in 
the genuine. After so much has been added as to make both 
as daik as they can become, a little more will turn the 
genuine to a pale yellow, giving a spectrum 7 . . 8- -9 — ; whereas 
that containing calumbia root will remain a fine red orange, 
with a spectrum 3-J . . - - 5 — . If too large a quantity of the 
hypochlorite be added the colour of the calumba root will 
change into a much paler yellow, scarcely differing from that 
in the case of genuine beer, and hence particular care must 
be taken to add it gradually, and in small quantities. By this 
means the adulteration of beer with two ounces of calumba 
root to the gallon may be detected with confidence, but much 
less than that would scarcely give reliable results, unless it 
