exciting-circuit. R R are resistances, and R S is the
resistance-switch, which is operated to put in more or less resistance
at R as the resistance of the charge in the furnace lessens or
increases. This switch may be automatically operated, and a suitable
arrangement for the purpose is a current-regulator such as is described
in the specification of English Letters Patent No. 14,504, of September
14, 1889, granted to William Henry Douglas and Thomas Hugh Parker.]

[Illustration:

T. PARKER.
ELECTRICAL FURNACE.

Patented Sept. 13, 1892.

FIG. 1.]

[Illustration: FIG. 2.

_Inventor
Thomas Parker_

_By his attorneys
Howson and Howson_

_Witnesses:
George Baumann
John Revell_]

[Illustration: Figure 11.--DIPPING OF MATCHSTICKS in France, about 1870.
The frame which holds the matches so that one end protrudes at the
bottom, is lowered over a pan containing molten sulfur. The
sulfur-covered matches are then dropped into a phosphorous paste. See
figure 12. (From FIGUIER, _Merveilles de l'industrie_, volume 3, 1874,
page 575.)]

Phosphatides and Phosphagens

The important phosphorus compounds in organisms are much more complex
than the simple salts, to which Nietzsche attributed such influence on
man's character. Long before he wrote, it was known that phosphoric acid
combines not only with inorganic bases to form salts, but with alcohols
to form esters. In the middle of the 19th century, Theophile Juste
Pelouze (1807-1867) extended this knowledge to an ester of glycerol.
This proved to be significant in several respects. Glycerol had been
shown by Michel Chevreul (1786-1889) as the substance in fats that is
released in the process of soap boiling, when the fatty acids are
converted into their salts. That it has the nature of an alcohol had
been demonstrated by Marcellin Berthelot. Instead of one "alcoholic"
hydroxyl group, OH, like ethanol (the alcohol of fermentation), or two
hydroxyl groups (like ethylene glycol), glycerol contains three such
groups. It was the only "natural" alcohol known at that time. That this
alcohol would combine with phosphoric acid could be predicted, but that
the ester, as obtained by Pelouze, still contained free acidic functions
and formed a water-soluble barium salt was a new experience.

[Illustration: Figure 12.--PAN FOR DIPPING MATCHSTICKS into phosphorus
paste, about 1870. The letters on the picture are: A, matches; B, water
bath; C, frame;