60 REPORT—1848., 
manufactured. This is a convincing proof that it is impossible to extract the 
whole of the colouring matter by means of boiling water, and that part of it 
must remain behind in some state in which it is insoluble in water. A quan- 
tity of madder was treated with boiling water until the liquor gave abso- 
lutely no more precipitate on the addition of muriatic acid. A very long 
boiling was necessary for this purpose. The colour of the madder was 
changed by this process from yellowish-brown, as it appears in the fresh 
state, toa dull red. It was then treated with boiling caustic potash ley. A 
liquor of a brownish colour was obtained, in which muriatic acid produced a 
gelatinous precipitate of a brown colour. This was separated by filtration, 
and, after being washed with cold water in order to remove all the muriatic 
acid, was treated with a large quantity of boiling water, in which it proved 
to be almost entirely soluble. The solution was light brown. It gave gela- 
tinous precipitates with acids, with lime and baryta water, alcohol and most 
salts. On evaporation it left a substance in light brown, transparent, brittle 
scales, which turned out to be pectic acid, much purer indeed than that ob- 
tained in the first instance from the aqueous decoction. No colouring matter, 
or any other substance besides pectic acid, seemed to be extracted by the 
caustic alkali. 
Another quantity of madder which had been completely exhausted by 
boiling water, was treated with boiling muriatic acid, and the liquid, after the 
boiling had been kept up for some time, was strained through a cloth and 
supersaturated with ammonia, which produced a pinkish-white precipitate. 
This precipitate was thrown on a filter and carefully washed. The liquid 
contained an abundance of lime and magnesia. A part of the pinkish-white 
precipitate was dried and heated to redness in a crucible. During ignition 
a gas came off which was without odour, and burnt with a blue flame, being 
probably carbonic oxide. After complete ignition it dissolved in muriatic 
acid with an effervescence of carbonic acid, but without leaving much car- 
bonaceous residue. On adding ammonia to the solution a white precipitate 
was again produced. The filtered liquid contained a large quantity of lime 
and a trace of magnesia. The precipitate consisted of alumina, peroxide of 
iron, phosphate of lime, and a trace of phosphate of magnesia. As it became 
probable from the preceding reactions that the pinkish-white precipitate con- 
tained oxalate of lime, the rest of it was treated with boiling dilute sulphuric 
acid. The liquid after filtration was evaporated. It gave crystals which 
were dissolved in alcohol to separate the sulphate of lime. The alcohol on 
evaporation gave colourless crystals of pure oxalic acid. Hence I infer that 
the following substances were extracted from the madder by means of mu- 
riatic acid :—lime, magnesia, oxalate of lime, phosphate of lime, alumina and 
peroxide of iron. The madder which had been subjected to the action of 
muriatic acid was now wel]-washed with water, and then treated with boiling 
caustic potash ley. A dark red solution was obtained, which, after being 
strained through a cloth, produced, on being supersaturated with an acid, a 
dark reddish-brown precipitate. This precipitate was thrown on a filter, 
and well-washed with cold water, to remove the excess of acid. I found 
this precipitate to dye mordanted cloth quite full, and of the same colours as 
madder itself. There could therefore be no doubt about its containing 
alizarin. Moreover, on treating the precipitate with boiling alcohol, a 
brownish-yellow liquid was obtained, which left on evaporation a brownish- 
red residue. A small portion of this residue being heated between two 
watch-glasses, an abundance of orange-coloured crystals of sublimed alizarin 
appeared on the upper glass. By treating the precipitate with boiling water, 
s 
A 
