Observations on Maddening 9 
impregnated witli the oily alkaline solution of alumine. 
As the method of dyeing indigo blue in all its shades is 
well known, it is needless to detail it ; and as to giving a 
rusty yellow colour, which may be done at little expense, 
nothing is necessary but to moisten the skains well with 
a solution of the sulphate of iron, to press them equally, 
and then to immerse them in a caustic ley of potash, 
which will precipitate and fix the oxide of iron of a dis- 
agreeable colour, but which will not fail to assume a rusty 
yellow shade by attracting and becoming saturated with 
the oxygen of the atmosphere : thus yellow will be more 
or less dark according to the quantity of the sulphate of 
iron in solution. More intensity and even more equality 
may be given to the rusty yellow by moistening the skains 
a second time in the ferruginous solution, and immersing 
them in the caustic ley. Care, however, must be taken 
not to use soda for this operation, because it generally 
contains sulphur, which blackens oxide of iron by mine- 
ralizing it. 
The skains coloured blue and rusty yellow, treated 
with oily alkaline solution of alumine, will produce, by 
maddering, dark purple and chamois colours, violet, li- 
lac, puce, mordore, &c. It may be easily conceived, that 
if, instead of maddering, the same skains prepared for 
maddering be dyed with kermes, cochineal, and Brazil 
wood, logwood, wood of St. Martha, woad, yellow wood, 
quercitron, yellow berries, &c. a great variety of colours 
will be obtained : the shades may even be varied ad infi- 
nitum by mixing the colouring ingredients with each 
other in different proportions. The affinity of adhesion 
of the colouring parts of all these ingredients varies also 
to such a degree, that the shades arising from a yellow 
or olive-green will be changed or totally metamorphosed 
by a second dyeing with madder, kermes, cochineal, or 
Brazil wood ; and will furnish orange shades, capucine, 
