Mery oe 
To2 SCIENCE. 
substances could be more unlike; but that chlo- 
rine should supply the place of hydrogen in a 
chemical compound was a conception which the 
dualists scouted as absurd. 
By the second investigation, as by the first, 
although Dumas gave a most fruitful concep- 
tion to chemistry, he only took the first step in 
developing it. His conception of chemical 
types was very indefinite ; and Laurent wrote 
of it a few years later, ‘‘ Dumas’s theory is too 
general; by its poetic coloring, it lends itself 
to false interpretations; it is a programme of 
which we await the realization.’”’ 
The third great investigation of Dumas was 
his revision of the atomic weights of many of 
the chemical elements, and in none of his work 
did he show greater experimental skill. His 
determination of the atomic weight of oxygen 
by the synthesis of water, and of that of car- 
bon by the synthesis of carbonic dioxide, are 
models of quantitative experimental work. 
That exuberance of fancy to which we have 
referred made Dumas one of the most success- 
ful of teachers, and one of the most fascinat- 
ing of lecturers. It was the privilege of the 
writer to attend the larger part of two of his 
courses of lectures given in Paris in the winters 
of 1848 and 1851, and he remembers distinctly 
the impression produced. Besides the well- 
arranged material and the carefully prepared 
experiment, there was an elegance and pomp 
of circumstance which added greatly to the 
effect. The large theatre of the Sorbonne was 
filled to overflowing long before the hour. ‘The 
lecturer always entered at the exact moment, 
in full evening dress, and held to the end of a 
two-hours’ lecture the unflagging attention of 
his audience. ‘The manipulations were entirely 
left to the care of a number of assistants, 
who brought each experiment to a conclusion 
at the exact moment when the illustration was 
required. An elegance of diction, an ap- 
propriateness of illustration, and a beauty of 
exposition, which could not be excelled, were 
displayed throughout; and the enthusiasm of 
a French audience added to the animation of 
the scene. 
To the writer, the lectures of Dumas were 
brought in contrast to those of Faraday. Both 
were perfect of their kind, but very different. 
Faraday’s method was far more simple and 
natural, and he excelled Dumas in bringing 
home to young minds abstruse truths by the 
logic of well-arranged consecutive experiment. 
With Dumas there was no attempt to popularize 
science: he excelled in clearness and elegance 
of exposition. He exhausted the subject 
which he treated, and was able to throw a 
[Vou. IIL, Siena 
glow of interest around details which by most 
teachers would have been made dry and profit- 
less. . 
In the early part of his life, Dumas was a 
voluminous writer, and in 1828 published the 
‘ Traité de chimie appliquée aux arts’ in eight 
large octavo volumes, with an atlas of plates 
in quarto. But, besides this extended treatise, 
two volumes of lectures are his only impor- 
tant literary works. He published numerous 
papers in scientific journals, which, as we have 
seen, produced a most marked effect on the 
growth of chemical science. But the number 
of his monographs is not large, compared with 
those of many of his contemporaries ; and his 
work is to be judged by its importance and 
influence rather than by the extent of the field 
which it covers. 
It was to be expected that a man working 
with such eminent success in so many spheres 
of activity, and at one of the chief centres of 
the world’s culture, should be loaded with 
marks of distinction of every kind. It would 
be idle to enumerate the orders of knighthood 
or the learned societies to which he belonged ; 
for, so far from their honoring him, he x ae 
them in accepting their membership. It is a 
pleasure, however, to remember that he lived 
to realize his highest ambitions, and to enjoy 
the fruits of his well-earned renown. France 
has added his name in the Pantheon 
‘Aux grands hommes la patrie reconnaissante.’ 
THE MONK-SEAL OF THE WEST IN- 
DIES, MONACHUS TROPICALIS GRAY. 
AN old English navigator and privateer, Wil- 
liam Dampier, while straining his eyes for Span- 
ish galleons in the Caribbean Sea during the 
season of 1675, was astonished at finding many 
seals sunning themselves on the Alacrane 
Islands: he was surprised, for he did not look 
for these animals in tropical waters, and hence 
he made voluminous notes of them.’ To this 
memorandum we are obliged to turn for all 
the knowledge that we have to-day of the rare 
form of which we offer the accompanying draw- 
ing. The specimen from which it was taken is 
now believed to be the only one in existence ; 
for the one which was in the British museum, 
collected in 1843 by Gosse and Hill, has been 
destroyed. The one which we figure is now in 
the new National museum at Washington: it 
was recently taken on the coast of Cuba, 
bought of some Cubans by Professor Felipé — 
1 Dampier, Voyage round the world, ii. 2, 3d ed., 1705, p. 23. 
