suppose, better for the picture, if its state were entirely neutral when
put away or framed; but if alum is added, acid must remain, since SIR
WM. says it combines with the size. What I should imagine is, that the
idea is good; but experience can only decide if the picture is better
put away in an acid condition. I should think there are more available
acids for the purpose, for alum has an injurious effect upon colour; and
a positive is nothing but colour, the organic matter of the paper
stained as it were by the silver: for, after all its washings and
application of re-agents, no silver can possibly remain in the paper.
The safest state therefore of putting away ought to be ascertained and
decided upon; as it is no use doing them if they fade, or even lose
their tones.

WELD TAYLOR.

N.B.--The iodized ammonio-nitrate paper will not bear exposure to the
sun; it will keep any {390} length of time, but should be kept in a
paper, and away from any considerable degree of light.

* * * * *

REPLIES TO MINOR QUERIES.

_Bishop Juxon's Account of Vendible Books in England_ (Vol. vi., pp.
515. 592.).--The following note in Wilson's _History of the Merchant
Taylors' School_, p. 783., solves the Query respecting the authorship of
this bibliographical work.

"_The Catalogue of Books in England alphabetically digested_,
printed at London, 1658, 4to., is ascribed to Bishop Juxon in
Osborne's _Catalogue_ for 1755, p. 40. But, as Mr. Watts, the
judicious librarian of Sion College, has observed to me, this is
no authority, the Epistle Dedicatory bearing internal evidence
against it. The author's name was _William London_, whence arose
the mistake!"

J. YEOWELL.

Hoxton.

_Dutensiana_ (Vol. vi., p. 376.; Vol. vii., p. 26.).--The following
statement, extracted from Querard's _France Litteraire_, sub voce
Dutens, will account for the discrepancies mentioned by your
correspondents with reference to the works of Louis Dutens.

Dutens published three volumes of _Memoirs_, which he afterwards
committed to the flames, out of consideration for certain living
characters. He then published, in three volumes, his _Memoires d'un
Voyageur qui se repose_, the two first containing the author's life, and
the third being the _Dutensiana_.

Your correspondent W. (Vol. vi., p. 376.) says that Dutens published at
Geneva, in six volumes 4to., with prefaces, the entire works of