In deriving a body from the water type I intend to express that to this body, considered as an oxide, there corresponds a chloride, a bromide, a sulphide, a nitride, etc., susceptible of double compositions, or resulting from double decompositions, analogous to those presented by hydrochloric acid, hydrobromic acid, sulphuretted hydrogen, ammonia etc., or which give rise to the same compounds. The type is thus the unit of comparison for all the bodies which, like it, are susceptible of similar changes or result from similar changes.

Originally a pupil of Liebig, I became a pupil of Dumas, Gerhardt and Williamson: I no longer belonged to any school.

Both died, ignored by most; they neither sought nor found public favour, for high roads never lead there. Laurent and Gerhardt never left such roads, were never tempted to peruse those easy successes which, for strongly marked characters, offer neither allure nor gain. Their passion was for the search for truth; and, preferring their independence to their advancement, their convictions to their interests, they placed their love for science above that of their worldly goods; indeed above that for life itself, for death was the reward for their pains. Rare example of abnegation, sublime poverty that deserves the name nobility, glorious death that France must not forget!