dd 
Alizarine has now ag cae madder indyeing Turkey red, The 
results are not quite Best same. Natural dyes are not absolutely 
pure, but more or less complex mixtures, and they yield in conse- 
dein in the hands of a skilful operator Doct tones which are 
not easily realised, or, at any rate, without more trouble than 
cheapness will allow, from the artificial substitutes. The following 
note, which has been kindly supplied by Dr. Hugo Müller, F.R.S., 
shows that the natural dye may even have practical advantages. 
But it is to be feared that these are not beyond the art of the 
chemist to imitate 
“It ‘is Sad nearly 20 years ago that the synthetical production 
of indig as first accomplished, and it was then generally 
eme that before long this remarkaple achievement of organic 
chemistry would, a n the case of oe seriously affect the 
natural product and pm Sok grav mportan e to the indigo 
planter; but in this cecus this ccc was du realized as 
suiparea. 
“ The process being too complicated and costly it could not 
compete with the natural indigo, and, with the exception of a 
tentative “application in cotton printing, the artificial indigo 
eral rely a landmark in the progress of. scientific 
chemist 
- Nevetthdlesi this discovery seems to have caused the indigo 
planters to bestir themselves and improve their methods of 
working, which in turn effected a considerable reduction of the 
rice and a consequent increase of production. 
* Meanwhile, however, the chemists were not idle, and a steady 
progress in the improvement of the synthetical processes was 
made, so much so that at the beginning of last year ER Badische 
Anilin and Soda Fabrik, SECETA On, made the announcement 
that they were now able compete with the natural indigo, by 
offering to the trade Es Hate bide (Indigotine) at the price 
of 17s. per kilo., which is a jog t the value of pure indigo-blue 
contained in comme rcial indig 
“ Thus, notwithstanding ihe heh reduced value of n soni 
indigo, the production of artificial indigo seems now more 
to have assumed a threatening importance to the indigo gió wor, 
which will have in all probability to be reckoned wit 
In an article published in the Chemiker Zeitung last 
November, Sigismund Lang discusses this subject in a spiri 
evidently lalesia to the artificial indigo, and points out that 
the price of 17s. per kilo. of the artificial indigo is still too high, 
inasmuch as the Codi of pure ban ay contained in the leading 
sorts of commercial indigo varies 6d.—15s. 9d.— d. ; 
but, what is still more to the po int, he calls attention to t the 
importance of the 2—10 per ait of toil (Indirubin, Indi- 
purpurin) contained in the bet er class of natural indigo, and 
which is said to be absent in the artificial. It appears that the 
presence of this colouring matter is all-important in the vat 
Fringe: as it causes the proper fixing of the indigo-blue on the 
fibre. Without indigo-red the goods a ej ts pue at hold the 
Cinane matter in much les a font a manner, and this is in fact 
the reason why Java indigo, which edi tarde little or no indigo-red, 
is altogether unsuitable for vat dyeing. 
