662 
Mr. S. Butler's Contributions to the (November, 
done. Let us take an instance which has in former days 
come under our personal observation. Here is G. K., blue- 
dyer at the Dash-wheel Works. He can set a warm-indigo 
vat and work it, turning out well-dyed cloths, rarely making 
a mistake, and keeping his vat in good working order. But 
does he know the principle of any one step in the process ? 
Did he ever know it ? Did the master to whom he was 
apprenticed ever know it, or his forerunners back to the 
earliest times when indigo-vats were worked in ancient 
India ? Most emphatically no ! He knows nothing of the 
transmutation of indigo-blue into indigo-white, or by what 
agency it is reconverted into indigo-blue after being depo- 
sited on the fibre. He knows by odour and colour when his 
vat is working right, and when it is sick ; but he never thinks 
that the right and the wrong conditions are due to the aCtion 
of certain ferments, and that it is possible to cherish the 
one and to repress the other. Lastly, not to prolong this 
illustration, he can, if he has had a quarrel with his em- 
ployer, occasion much trouble by throwing lumps of copper 
sulphate into the vats. But he has not the faintest idea 
how this mean piece of rattening aCts. He does not know 
that salts of copper have the power to transfer oxygen from 
the atmosphere to organic matters with which it is in con- 
tact, thus converting the soluble white indigo into the 
insoluble indigotine, when it has no longer the power of 
attaching itself to the wool. 
Lastly, it is well known that in the art of indigo-blue 
dyeing, as well as in dyeing cochineal-scarlets, a variety of 
improvements have been made. The process has been sim- 
plified, and a variety of useless ingredients have been 
omitted. But has this ever been done consciously, or with 
increasing perfection has it come to be done unconsciously ? 
We trow not: a number of fortuitous steps — very much as 
in the supposed formation of species by Natural Selection — 
have led up to the present state of the art. Some one of 
the useless ingredients was accidentally omitted, or the 
supply fell short, and the dyer, going to work without it, 
obtained as good a result as if he hadi followed the old tra- 
ditional receipt. But why this or that ingredient was 
needless he never asked. There was also in dyeing, as in 
other arts, experimentation, but it was a blind tapping, — 
again like the aCtion of Natural Selection. 
But when a really great improvement was needed, men of 
conscious knowledge were needed. Schiitzenberger and 
De Lalande discovered a process by which oxygen could be 
withdrawn from organic matter, both efficaciously and regu- 
