456 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS; [December 2,1871, 
with cream of tartar or oxalate of potash, an orange-red 
precipitate. Alumina removes the whole of the colour¬ 
ing-matter from an aqueous solution. As cochineal is 
an expensive dye-stuff, it is subject to much fraud and 
cochineal is left in contact with three parts of ammonia 
for several weeks, a chemical action ensues, by which 
the ammonia loses one equivalent of hydrogen, which 
unites with an equivalent of oxygen of the carminic 
adulteration. One of the most common frauds is prac- acid, giving, rise to water and an amide compound, car- 
tised at Nismes and other 
largely prepared. 
places where perfumery is j minamide. Adopting M. 
Schiitzenberger’s 
formula for 
The cochineal in those localities is carminic acid, the change may be thus represented: 
NIL = PRO + 
Water. 
put into water for a short time, by which a part of its 
colour is extracted; it is then dried, and either sold as 
black cochineal, or placed in a sack and shaken with 
talc or sulphate of lead, and sold as white cochineal. 
This fraud is easily detected by grinding the cochineal 
and mixing it with water, when the talc or sulphate of 
leads falls to the bottom. Good cochineal does not leave 
above five or six per cent, of ash. 
C 9 H s 0 5 + 
Carminic Acid. Ammonia. 
c 9 h 9 no 4 . 
Carminamide. 
This compound is also used for dyeing, but before em¬ 
ploying it for this purpose it is necessary to add 4 per 
cent, of alumina, in the state of jelly, to the mixture de¬ 
scribed above. The mass is then slowly evaporated to» 
the consistence of a thick paste. By this means all ex¬ 
cess of ammonia is expelled. This preparation is used 
It is often advisable before buying cochineal to deter¬ 
mine its tinctorial power. This may be ascertained by in i -n n , ■, • ■. ~j i 
, n ,, L r xi. a j. J i • i, for dyeing silk, and to produce violet and mauve colours 
two or three methods. In the first, equal weights of the ; -n j 
51 ° 1 on woollen goods. 
Carmine Lakes .—These very beautiful pigments are 
prepared from a decoction of cochineal, and not from 
carminic acid, the animal matter which the insect con- 
to be necessary to their production. 
The mode of preparing the finest qualities is kept a 
secret by the manufacturers; but I will describe two- 
processes, which give very satisfactory results. The 
first consists in boiling one pound of ground cochineal 
with two gallons of water, to which has been added one 
ounce of alum. It is then boiled for three minutes, the 
liquor is allowed to settle, and, after having been kept 
for several days, about an ounce of a bright carmine 
lake is produced. For the alum employed in this pro¬ 
cess cream of tartar can be substituted. The second 
process consists in boiling for three hours two pounds of 
powdered cochineal in thirty gallons of water. To this- 
is added three ounces of pure saltpetre. The liquor is 
then boiled again and left to settle. The clear liquor is 
run off, and after two or three weeks yields a fine car¬ 
mine lake. 
As these lakes arc expensive, they are often adulte¬ 
rated with starch, kaolin, vermilion, etc. The complete 
solubility of pure carmine lakes in ammonia affords a 
ready means of detecting these adulterations. 
Kcrmes. —This colouring iftatter is also derived from 
a variety of Coccina , which lives on the species of oak 
called Quercus coccifera. The young female animal fixes- 
itself under the epidermis of the leaves or young shoots 
of the oak, in the early part of spring. As the insect 
grows, it gradually swells out the epidermis, covering* 
the surface of the leaves or branches with a multitude of 
excrescences. During this period it deposits its eggs. 
In Spain and the south of France, during the month 
of June, or just before the eggs produced would bo 
hatched, the animals are removed and destroyed by 
placing them in the steam from heated vinegar. 
Although this colouring-matter is seldom used in 
England, it is extensively employed in the south of 
France, in Spain, Morocco and Turkey, to dye morocco 
leather, and to dye w r oollen cloth with that particular 
shade which characterizes the cap called “fez,” worn by 
the Asiatics. 
If the colour is not so brilliant as that of cochineal, it 
has the advantage of not being changed by soap or di¬ 
lute alkalies. It is also employed at Milan, Rome and 
Florence to colour a very favourite beverage known as 
alkermcs. The colour-giving principle of this insect is 
identical with that of cochineal, and has been used as a 
cochineal to be assayed, and of one of known value, are 
treated with alcohol or a solution of alum. The solu¬ 
tions thus obtained are poured into tubes and placed in 
a colorimeter. This is an oblong box, which has two | , • 
apertures at each end and two on the top, in a direct | rp\ m3 ’,i 1 ,^f' Cai p 11 
line with the end apertures. The tubes are placed 
through the openings on the top, and on looking through 
the end apertures, any difference in intensity of colour 
between the two liquids can be observed. If a difference 
is detected, alcohol or water is added to the stronger 
liquor until there is perfect uniformity of tint. Accord¬ 
ing to the amount of dilution required is the relative 
value of the cochineals. 
A good process was published by the late Dr. Penny, 
of Glasgow. It consists in exhausting a gramme of 
cochineal with fifty grammes of potash solution, 
this extract is further diluted with 100 grams of 
water. The solution thus obtained is mixed with a 
graduated solution of ferricyanido of potassium (one 
gramme of salt to 200 grams of water) till its colour 
changes to a dark brown. A solution of bleacliing-pow- 
der of known strength can also be used for the same 
purpose. The best method consists in dyeing equal sur¬ 
faces of flannel in a bath composed as follows :—• 
For Scarlet Tints. 
Grams. 
Water.1250 
Cream of Tartar 
Tin Composition 
Cochineal . . . 
For Crimson Tints. 
2 
2 
1 
Grams. 
Water.1250 
Cream of Tartar. 0*75 
Alum. 1-50 
Cochineal. 1 
The pieces are then washed and dried, and by a com¬ 
parison of the relative intensity of shade the value of 
the cochineal is determined. 
The chief employment of cochineal is for dyeing wool, 
but it is also employed in calico printing to produce 
pinks and reds in steam styles. 
It will no doiibt be interesting to you to know how* to 
determine whether a pink has been produced from a 
dyewood, a cochineal, or from madder. All these colours 
are destroyed by chlorine or bleaching-powder. A boil- _ _ _ __ j _ 
ing soap solution destroys the wood pinks, communicates i dye in the East from time immemorial, 
a crimson hue to the cochineal dye, and brightens the j 
madder colour. Dipped in a rather dilute solution of' 
hydrochloric or sulphuric acid, fabrics dyed with cochi-! 
neal are not affected, while those dyed with madder or ; 
woods assume a yellow tint, which becomes purple when ' 
placed in milk of lime. These cloths, however, if sub- j 
sequently soaped, will yield their colour if dyed with 
wood, but not if dyed with madder. 
Ammoniacal Cochineal. —When one part of ground 
Gum-lac .—This is another variety of the Coccina , 
which lives especially on the Ficus, or fig-tree. They 
reproduce themselves with such rapidity and in suck 
numbers that they entirely cover the surface of the 
branches of the trees on which they are deposited. 
Owing to a resinous fluid which they secrete, they form 
solid masses, which are often a quarter of an inch thick, 
all round the branches, and adhere very firmly to them. 
The natives break off these branches just before the 
