per now extinct, and one which, unfortunately for us, it seems impossible
to reproduce.

T. L. MANSELL.

Guernsey.

_Conversion of Calotype Negatives into Positives._--At the second meeting
of the British Association at York, Professor Grove described a process by
which a negative calotype might be converted into a positive one, by
drawing an ordinary calotype image over iodide of potassium and dilute
nitric acid, and exposing to a full sunshine. Not being able to find the
proportions in any published work, can any of your numerous readers give me
the required information; and whether the photograph should be exposed in
its damp state, or allowed to dry?

G. GRANTHAM.

_Albumenized Paper._--Mr. Spencer, in the last number of the _Photographic
Journal_, in describing a mode of preparing albumenized paper, states he
has never found it necessary to iron it, as the silver solution coagulates
the albumen the moment it comes in contact with it, "and I fancy makes it
print more evenly than when heat has been employed." But Mr. Spencer uses a
nitrate of silver solution of 90 or 100 grains to the ounce, while DR.
DIAMOND recommends 40 grains. Now as it is very desirable to get rid of the
ironing if possible, my Query is, Will the 40-grain solution coagulate the
albumen so as to do away with that troublesome process?

P. P.

* * * * *

Replies to Minor Queries.

_Table-turning_ (Vol. ix., p. 39.).--The following conclusions, from an
_expose_ of the laws of nature relating to this subject, have been
submitted to the world, at the end of a series of articles in the _Revue
des Deux Mondes_, by M. Babinet, of the French Institute:

"1^o. Que tout ce qui est raisonnablement admissible dans les curieuses
experiences qui ont ete faites sur le mouvement des tables ou l'on
impose les mains, est parfaitement explicable par l'energie bien connue
des mouvemens naissans de nos organes, pris a leur origine, surtout
quand une influence nerveuse vient s'y joindre et au moment ou, toutes
les impulsions etant conspirantes, l'effet produit represente l'effet
total des actions individuelles.

"2^o. Que dans l'etude consciencieuse de ces phenomenes
mecanico-physiologiques, il faudra ecarter toute intervention de force
mysterieuse en contradiction avec les lois physiques bien etablies par
l'observation et l'experience.

"3^o. Qu'il faudra aviser a popularis