144 
llEPORT- 1847- 
decomposed by boiling concentrated nitric acid, men heated on platinum 
toil it burns without melting, leaving a considerable ash. It seems that the 
pectic acid from madder retains in combination with it a portion of colouriw 
matter, from which it cannot be separated. Hence the red colourwith whidi 
It dissolves in alkalies. 
Concerning the two fats which I mentioned above as constituente of the 
rown precipitate, I have little to say. They also retain in combination i 
quantity of w curing matter, from which I l.ave found it impossible to seps- 
ra e tiem. Tbc^y are both soluble in alcohol, but one more so than thf 
otier. One of them di.ssolves with rubiacui in percliloride of iron, the other 
not. ihe former Is more easily fusible than the latter, but both melt below 
the temperature of boiling water. 
I shall conclude this paper with some practical deductions which I haie 
made from the experiments detailed in tJic preceding. 
ew subjects connected with the .arts fiavo raised so much discussion » 
tne nature of the process of madder-dyeing. The investigation of Robiquel 
on tins subject, instead of clearing it up, seemed oulv to add to its com- 
pexi.j. He considered his alizarin as the subsiauce mainly coDcerned is 
the production of iimdifer colours. This has been dciiicd by othere, tJiongb 
uu on iti>ufTicjent grounds. A remarkable discovery in regard too^addf^ 
fk ""seiitial in this process, it was fouail 
tnat madder, it not grown on calcar.^ous soif, is incapable of produciogfa^t 
colours, but that if n, tins ease chalk bo added to tbe madder duringdycing. 
or If (^IcareouR water bo employed, the desired effect is produced. This 
a am has given rise to endless diHcussioiis. It was found hy Persoz that the 
quantity of lime added to alizarin impaired its colouring poww 
inlv in inaddcr-dyeiiig appeared to him au 
‘' mystery. I will not enter further into the disputes on thissuir 
voV/ia^n 1 "'y seems to me that former in- 
e^tigators have erred in supposing that madder confaiiied only one colouring 
Sid .llfintVfT * - there are two, perfectly distinct 
the nrop ’ f l*^*!*” wJiioli perform distinct functions iluriae 
clur^ n.l ^ above, that of the tvo 
j i alizarin uml rubiaciii, the former is the only one that h 
tatp nrndii/> . y**. ® and further, that the brown precipi* 
tbL^ulTl a watery extract of madder contains thewholsuf 
acid tht^vm i fl precipitate. al>er being fri'ed from rilexcesof 
n^ecio aJ Iff'*"' alizarin contained in the brown 
Le W liti!!’ f|''«ntiky of lime, clialk. soda, or any alka- 
before <^arbo.iated, be added to the brown precipitate 
prove this I mnt - ‘® ''"X increased. In order » 
2 and S uirl m mordanted doth, all of the same size. Kos. I 
Nos 4 '^ind r ‘tsual way ivltli acetate of alumina, airi 
mia^uVnf h 1 ^ dyed with a certai" 
the broln^ • Nos. 2 and 5 writh the same quantity of 
a very smiirrmnm*l‘*‘’’ r ? bad previously been addd 
litv o^f b^oL r" • «Hue water ; Nos. 3 and 6, lastly, with the same quso- 
pe?formed rlj ® *'*"6 water. The dveing vr« 
for the LmTLu ^ same quantity of water, anj 
exhibited a /Hr flifJ ” r V/”^ No%r I found at the conclusion that No- 8 
and No. 5 a ninn)*^ fuller, and more brilliant shade of red than No. I- 
and 6 showpd intense purjilc colour than No. 4 . whereas N'lis- ^ 
owed hardly any colour at all. Now I can offer only one explanation 
