136 
REPORT—1847. 
On Colouring Matters. By Dr. Schunck. 
At the meeting of the British Association at Southampton I gave a shat 
account of my experiments on the colouring matters of madder, i hw 
continued this investigation, and iiave found tJii; exlwit of the subject 
great to allou' nio to devote mv attention to unv other of the colonrini' mr. 
retjuireu lor every jiouiKl of nmdder. To this fluid . 
sulphuric or muriatic acid, is added in slight excess. Nitric acid iiiusiiu* 
be used for the purpo.se. Oxalic acid is best adapted for the purpoff, »t 
can aftenvards bo completely removed by chalk. The acid prducesat -i 
rown precipitate, which is s«’])aratc:d by filtration and washed with wiii 
until the excess of acid is removed. The percolating fluid is yellow. Tl« 
rown precipitate consists of six vegetable substances, viz. two coloiiTi(* 
matters, kinds of fat, peclic acid and a substance of an intensely bitw 
aste, which I am as yet unable to refer to any known class of bodies. IV 
vviiole quantity of colouring matter contained in the anueoue atract of uijii- 
uer IS precipitated by the addition of a strong acid. In proof of this I todt 
a quantity of the aqueous extract, added sulpliiirin acid, separated the bmt 
preciptate by filinition and rcinovoif the excess of acid witli cold water, iwi 
tnen boiled it with water, into which a small piece of mordauted clolii"® 
introduced. Ihe cloth assumed the sumfi colours which it would haveiiow 
al Ith^' -r* ‘ acid bad been added I put chalk 
citr! nn J I saturated, and I then found after filtering that it foniniuflf 
cated no colour whatever to mordanted doth. ^ 
shall rill « liobiquets Alizarin, and the oihd 
by acids iu t\ dontaiiifid in the brown precipitate produ^ 
K nrJdn n. 1° «>-der to obtain then., tto 
dissolved A treated with boiling alcohol until nothing moff “ 
consistiiiff nrineit *’^tin>wliat gelatinous massisleft hehui 
the two coloSni’'' alcoholic fluid, which coB^» 
coLuT Aft ” fats, has a darkbrow.)hh.yeIk« 
of a dirtv rml'n’^, and then evaporated to dryuc^S a r«id.c 
washed witHobl ^v.* '**' '‘‘‘m®:""* is placed on a lilter^ 
becomes eoLrllr OmT' ‘ing fluid, wiich is at 
substance with n this fluid leaves a traaspareni yfj^ 
purrwater b t mentioned above. This substancTb^duble? 
tated on adding acid to d containing acids, and hence it 
precipitate with wni J •extract of madder; but on wasiinp tV 
In order So obtain ^ H ^eimived it begins to diss^u- 
long as it still 0011111111 ^^*^^’ ^ 1 ^ precipitate must only be nasiie^ 
mass left uiidissolved hv ^ ‘mil this substance , 
the fluid is filtpm,l 1 f ‘s then treated with boiling n^Uer. 
flocks w,,H,eo, kt n°r deposits a quantity of ^ 
peated undl tho t iIiL"‘r-T Thi* process mM 
rubiaii be still led i., ‘•pp‘«its nothiog more on cooling* ^ • 
of the boiling flidd T « boiling water, 
remove this subst^nr. much impeded, and it is therefore adrisabh 
ubstance completely with cold water previously to treating 
