1815,J ‘Smithson Tennant, Esq. 91 
once original and delicate, with which he could animate and em- 
bellish the most unpromising subjects. 
The delivery of these Jectures may be considered by some persons 
as a very trifling occurrence in the life of a man of science; but 
the writer has thought it well worthy of a place in the present nar- 
rative, not only as affording a new proof of the extent and variety 
of Mr. Tennant’s powers, but because it exemplifies in a very 
pleasing manner one of the striking and amiable peculiarities ‘of his 
character. As he had a remarkably clear perception of the most 
refined scientific truths, so he possessed a power of explaining and 
illustrating such subjects, which might jusly be deemed unrivalled. 
Without any ostentation of learning, be had a peculiar delight in 
communicating knowledge to others; but especially, in unfold- 
ing the principles of science to young persons, capable and de- 
sirous of receiving such information ; and he partook with the most 
lively sensibility in the emotions of curiosity, pleasure, and sur- 
prise, which his lessons seldom failed to inspire. He entirely dif- 
fered from those who condemn as trifling and superficial, that in- 
creasing taste for scientific knowledge in the higher and more 
opulent classes, to which many circumstances have lately contri- 
buted. He considered the difiusion of this taste among the young, 
the idle, and the wealthy, though liable in some cases to degenerate 
into affectation, as being in its general effects highly beneficial ; 
both by affording to an important class of society additional sources 
of intellectual pleasure and new objects of rational pursuit; and 
indirectly, by obtaining for science and its professors a greater 
degree of public consideration and respect than they have enjoyed 
in any former age. 
In the spring of the year 1813 Mr. Tennant delivered before 
the Geological Society a lecture on the principles of mineralogy. 
After taking ‘an historical view of the subject, and pointing out 
the merits and defects of the principal writers by whom it had 
been systematically treated, le took an enlarged view of the 
science, regarding it as that branch of chemistry which treats of 
the definite compounds that are found native in the mineral king- 
dom, and whose crystalline forms and other properties are to be 
studied and described in the same manner as those of any other 
chemical substance. He then noticed several artificial productions 
which are analogous to those of Nature; and amongst the rest a 
silicate of copper, which he had formed by adding a solution of 
that metal to an acidified liquor silicum, which he conceived might 
perhaps be identical with the Siberian mineral called Dioptase. 
Mr. ‘T. had communicated to the Geological Society some time 
previously (in the year 1811) the result of his investigation of the 
native boracic acid, which he had discovered in a collection of vol- 
eanic substances from the Lipari Isles, and which has since been 
found in the island Voleano by Dr. Holland. ‘This communication 
was published in the first volume of the Transactions of the Geolo- 
gical Society. 
