140 Observations on Maddening. 
to the action of the boiling water* It is needless to ob- 
serve, that there is no danger of spoiling the colours by 
soap and alkaline carbonates, when the maddering, in- 
stead of being directed with a moderate heat, has been 
carried to ebullition, as is practised in many dye-houses ; 
but, in this case, the colours obtained are more difficult 
to be cleared. 
As water charged with oxygenated muriatic acid easi- 
ly carries away the colouring parts of madder, as well 
as other vegetable and animal substances, by decompos- 
ing them ; and as acids more concentrated may, in their 
turn, take from the stuffs the colourless alumine and the 
oxide of iron, it is impossible for me to adopt the idea of 
a chemical combination of the colouring parts with alu- 
mine and metallic oxides, which, in my opinion, when 
fixed and coloured on any stuff, form only compound ag 
gregates. 
The clearing of objects printed on a white ground re- 
quires modifications, which I shall detail on a future oc- 
casion, when I find leisure. It will therefore be suffi- 
cient at present to state, that after continuing for some 
time my experiments on the Turkey red, inserted in the 
Jlnnales de Chimie for the year 179&, I at last found a 
red much more beautiful and durable than that of the 
Levant, by fixing alumine on cotton, thread, and linen, 
by an alkaline solution of this earth mixed with linseed 
oil. The following is the process I employed. 
(To be continued *) 
