NOTES ON ALKALOIDS AND OTHER SUBSTANCES. 
47 
Woad (Isatis) contain a yellowish substance called Indig ogen, 
which is converted into Indigo-blue on exposure to air, I suggested 
some years ago that B. luridus contained this Indigogen. I ex- 
tracted about 2 lbs. of the fungus with alcohol, and obtained a 
brownish yellow extract becoming rapidly blue in air. But indigo 
is a very stable substance, which may be reduced by organic matter 
to colorless Indigo-white, and then again oxidized to Indigo-blue 
on exposure, and this transition may be effected any number of 
times. The pigment of Boletus, on the other hand, rapidly passes 
from yellow to blue, and from blue to brown ; while in the blue 
state it can be again reduced to yellow; but when it has once 
become brown it seems to be destroyed, as I could not by any means 
restore the blue color. Indigo gives in the spectroscope a very 
definite absorption band : in the blue matter of Boletus I could 
not detect any special band. The finally resulting brown matter 
was amorphous, acid, soluble in water and alcohol, and appeared 
very similar to the humus-like bodies extracted from peat, &c. It 
did not contain nitrogen. I could not, however, obtain the blue 
matter in a pure state on account of its rapid decomposition, but 
it certainly contains neither indigo nor aniline. It has been stated 
that B. cyanescens yields a brownish yellow pigment, turned deep- 
blue by sodium hypochlorite, and unaffected by weak alkalies or 
acids, and that similar reactions occur with B. luridus. Satanas, 
calopus, and variegatus. I found, however, that B. luridus was 
simply bleached, and not blued, by sodium hypochlorite, hlo 
cyanogen compound is present. 
Now as to the Alkaloids, An alkaloid means literally a com- 
pound resembling an alkali. The alkalis are potash, soda, and 
ammonia ; they have the well-known effects of blueing vegetal 
reds, of forming salts with acids, of an acrid taste, a soapy feel and 
characteristic odors. Certain compact groups of carbon and 
hydrogen, which can pass entire from compound to compound, are 
thence called compound radicles. The alkali ammonia, then, being 
composed of one atom of nitrogen to three atoms of hydrogen, can 
have its hydrogen replaced by one or more of these compound 
radicles. So we form a “ compound ammonia,^* or “ amine.'’’ These 
“ amines” partake of the characters of the alkali ammonia, and 
hence are called alkaloids. They are generally colorless, alkaline 
in reaction, and form crystallizable salts by union with acids. 
As a rule, they are powerful in their action on the system, hence 
the plants which contain notable quantities of them are either 
medicines, poisons, or perhaps condiments like pepper, or semi- 
medicinal foods like tea or coffee. For this reason their study is 
a most important feature of plant-chemistry. 
From ammonia (NHg), by substituting the “ compound radicle ” 
methyl (CHg) for hydrogen, we get a volatile alkaloid tri-methyl- 
amine, a colorless liquid with a powerful fishy odor ; in fact it is 
the cause of the smell of decayed fish, and is extractible from 
herring-roes, from crayfish, and from other fishy sources. It is 
