threadbareness--making itself manifest. This is simply because the
colour or dye only penetrates a very little way down into the substance
of the felt, until, in fact, it meets the proofing, which, being as it
ought to be, a waterproofing, cannot be dyed. It cannot be dyed either
by English or German methods; neither logwood black nor coal-tar blacks
can make any really good impression on it. Cases have often been
described to me illustrating the difficulty in preventing hats which
have been dyed black with logwood, and which are at first a handsome
deep black, becoming rather too soon of a rusty or brownish shade. Now
my belief is that two causes may be found for this deterioration. One is
the unscientific method adopted in many works of using the same bath
practically for about a month together without complete renewal. During
this time a large quantity of a muddy precipitate accumulates, rich in
hydrated oxide of iron or basic iron salts of an insoluble kind. This
mud amounts to no less than 25 per cent. of the weight of the copperas
used. From time to time carbonate of ammonia is added to the bath, as it
is said to throw up "dirt." The stuff or "dirt," chiefly an ochre-like
mass stained black with the dye, and rich in iron and carbonate of iron,
is skimmed off, and fresh verdigris and copperas added with another lot
of hat-forms. No doubt on adding fresh copperas further precipitation of
iron will take place, and so this ochre-like precipitate will
accumulate, and will eventually come upon the hats like a kind of thin
black mud. Now the effect of this will be that the dyestuff, partly in
the fibre as a proper dye, and not a little on the fibre as if
"smudged" on or painted on, will, on exposure to the weather, moisture,
air, and so on, gradually oxidise, the great preponderance of iron on
the fibre changing to a kind of iron-rust, corroding the fibres in the
process, and thus at once accounting for the change to the ugly brownish
shade, and to the rubbing off and rapid wearing away of the already too
thin superficial coating of dyed felt fibre. In the final spells of