eople use this as a kind of an intoxicant?"

"If used to excess it has an exhilarating influence, on account of its
tonic properties."

"I have often thought it was wonderful," said Harry, "that people all
over the world have some kind of a weed or plant that they use to
stimulate themselves with."

"There seems to be a universal instinct in man to select the strong and
bitter principles for that purpose. The aborigines of Central America
used rolled tobacco leaves ages before Columbus was born; and the coca
leaf, chewed by the lowest orders of the Peruvians, was for ages, and is
now, their main source of strength and comfort. So opium, hemp and the
betel-nut have been used by eastern Asiatics from the remotest
antiquity; and the same is true of the pepper plants of the South Sea
Islands and the Indian Archipelago; also of the thorn apples used among
the natives of the Andes, and on the slopes of the Himalayas. In
northern Europe the ledum and the hop have been so used, and in Siberia
the narcotic fungus has been eaten from time immemorial."

At that moment Baby appeared on the scene, his hands and one side of his
head dyed a beautiful red, presenting a ludicrous appearance. The first
glance at him was one of astonishment; but realizing that he had been
testing George's newly made dye, all burst out in laughter at the
amusing sight.

"You really look like a red angel," was George's greeting, and Baby
seemed to relish the joke. From that time forward Baby's name was "Red
Angel," but it took him some time to learn what the new title was. It
took him much longer to acquire it than it did to learn what honey
meant.

"Red Angel is certainly a very smart little chap," said the Professor,
with a laugh, "because he was really doing what is done in the dyeing
art and in chemistry every day, furnishing a test sample."

"Test sample; what is that?"

"In the art of dyeing it is the custom, before commencing to dye goods,
to make a test sample, and all goods dyed must come up to the standard
set by that sample. That is called the 'test sample.'"

"But how do the chemists use it?"

"In the analyses of chemicals one of the processes is by what is called
the color metric test--that is, the test by color. The chemist makes a
solution with a known quantity of the element in it which is of full
strength and purity, and is therefore of a well-defined color. Now, if
any substance is to be analyzed, the same reagent is used in th