114 TRANSACTIONS OF THE [MAR. 21, 
for the snowy-white alkaloid of cinchona he was disgusted when 
he obtained a dirty brown mass; but the next moment he was filled 
with joy when, on dissolving it in alcohol, he obtained that beauti- 
ful coloring-matter which he called mauve. From that simple ex- 
periment there started an industry that to-day is probably worth 
fifty millions of dollars to the world every year. 
Owing to the brilliancy of the results of the researches of Perkin 
and Hofmann (who, by ‘the way, was a pupil of the great Leibig), 
organic chemistry soon had an army of enthusiastic investigators 
delving into its secrets and unearthing new substances almost daily. 
The dyes and coloring-matters received a great deal of attention, 
and after a time both alizarine and indigo yielded to synthetic 
chemistry ; and to-day there is not an organic compound ‘that we 
can find the true constitution of that we cannot make in our labora- 
tories. 
I have spoken of aniline. Like the oil of bitter almonds it is 
derived from benzol, one of the products of coal-tar. 
The benzol is first treated with nitric acid, making what we call 
nitrobenzol. 
This nitrobenzol is next mixed with iron filings and acetic acid, 
when aniline oil, as it is called, is formed, and this is the basis of the 
aniline colors; think of the industry and wealth brought into the 
world by such simple experiments. 
The first step in the successful imitation of a natural product is 
to ascertain with certainty its constitution, into what products it is 
most easily separated, and how these again break up into simpler 
ones already known Kolbe knew that salicylic acid could be readily 
converted into carbolic acid, carbonic acid being liberated. He rea- 
soned, then, that if he could make carbonic acid act upon and com- 
bine with carbolic acid, salicylic acid would probably result. By 
the intervention of metallic sodium the reaction was accomplished ; 
but.sodium is too expensive a metal for such a purpose, hence he 
sought and found a cheaper one in caustic soda. What the latter 
lacked in energy was compensated for by simply raising the temper- 
ature. 
Baeyer’s recent synthesis of indigo is of no importance to the dyer 
at present, because his method is too circuitous and expensive ; but 
it is no less the great achievement of a master-mind. Another may 
modify his method and make it profitable. 
Baeyer’s synthesis of indigo-blue furnishes a most instructive ex- 
ample of reversed operations. It had long been known that when 
indigo is oxidized with nitric acid isatine is formed; so Baeyer 
reasoned from this that he must be able to reduce isatine to indigo- 
blue, and in this he succeeded by the aid of phosphorus and chlo- 
ride of phosphorus. The next step was to prepare the isatine. 
Oxindole can be made from isatine ; therefore Baeyer thought he 
could make isatine from oxindole, and after a few unsuccessful 
efforts he finally sueceeded in making isatine. This completed his 
