434 
COCHINEAL COLOURING. 
by Varentrapps’s method, gave a platinum salt, which left after ignition *092 
platinum, equal to *013 nitrogen. 
The results are not sufficiently accordant to allow of the precise deduction of 
the formula :—■ 
I. 
Pure Alkaloid. 
C . 78-3 .. 
H . 11-2 .. 
N .. 
The formula which agrees best with I. is C 2G H 21 NO ; that most applicable 
to II. is C 25 H 22 NO :— 
156 ... 
.... 78-39 
c, 5 .... 
.. 150 .. 
.... 77-33 
21 ... 
.... 10-55 
h 22 .... 
22 .. 
.... 11-34 
14 .. 
.... 7-04 
N .... 
14 .., 
.... 7-21 
8 ... 
.... 4-02 
O .... 
8 .. 
.... 4-12 
199 
100-00 
194 
100-00 
II. hi. 
Platinum Salt. Platinum Salt. 
.. 77-3 . 
.. 11-9 . 
. 773 
The latter formula also gives an equivalent number more closely corresponding 
with that deduced from the ignition of the platinum salt, but nevertheless the 
uneven number of the carbon equivalents renders it a very improbable one. 
To my great regret, I have had no opportunity of repeating the analysis with 
more care ; hence the results are not so satisfactory as I could wish, and but for 
the reasons above given, I would willingly have withheld them. 
COCHINEAL COLOURING. 
For the following formula we are indebted to Dr. George Dickson, of Edin¬ 
burgh :— 
u Cochineal colouring may be prepared without admixture of carbonate of 
potash, alum, etc., as follows :— 
Take of— 
Cochineal in powder, 1 oz. 
Spirit of wine, 2 oz. 
Water, 6 oz. 
Liq. Ammon. Fort., q. s. (about -rn.viij). 
a Mix the spirit and water, and in three ounces of the mixture, heated to near 
the boiling-point in a flask, infuse the cochineal for fifteen minutes. Pour the 
infusion into another vessel, and repeat the process with three ounces more of 
the mixed spirit and water ; and a third time, with the remaining two ounces. 
Let the liquid stand till cold, when some fatty matter will rise to the surface ; 
filter, adding spirit and water, up to eight fluid ounces. Lastly, add sufficient 
Liq. Ammon. Fort, (about mi to *i) to change the infusion to the desired tint. 
“ The objections to the use of carbonate of potash, alum, etc., are :—1st, the 
colouring-matter is thrown down as a lake, and after some time, forms a layer 
at the bottom of the containing vessel, requiring the addition of ammonia to 
redissolve and keep it in solution ; and 2nd, it does not keep well. On the 
other hand, the advantages of this preparation are :—1st, the colouring-matter 
remains in solution, and 2nd, it keeps well, and has no unpleasant odour.” 
