it your exciting
mixture (say aceto-nitrate and gallic acid, solution of each 20 minims,
distilled water 1 ounce), and spread it evenly over with a scrap of
blotting-paper. Float your paper two minutes, remove and blot off; this
ensures perfect evenness, especially if the paper is large. You may thus
excite half a dozen papers with little more trouble than one.

THOS. L. MANSELL.

_The Double Iodide Solution--Purity of Photographic Chemicals._--The
observations of MR. LEACHMAN upon the solvent powers of iodide of potassium
(Vol ix., p. 182.) are perfectly correct, but I believe our photographic
chemicals are often much adulterated. The iodide of potassium is frequently
mixed with the carbonate. DR. MANSELL writes me word, in a comment upon
your note upon his communication, "What I used was _very_ pure, having been
prepared by Mr. Arnold with great care: it was some that had gone to the
Great Exhibition as a sample of Guernsey make, and obtained a medal." I
have this day used exactly seven ounces avoirdupois to make a pint of the
iodizing solution, which, within a few grains, agrees with my former
results. Nitrate of silver, I am informed upon a most respectable
authority, has been adulterated thirty per cent., and without careful
testing has eluded detection; but I am inclined to think our cheapest
article has come in for its largest share of mixture. I have lately
perfectly failed in the removal of the iodide of silver with a _saturated_
solution of what I purchased as hyposulphite of soda, but which could have
been little else than common Glauber's salts; for upon applying a similar
solution of some which was made by M. Butka of Prague, and supplied me by
Messrs. Simpson and Maule, the effect was almost immediate, demonstrating
how much we are misled in our conclusions, from believing we are
manipulating with the same substances, when in fact they are quite
different.

HUGH W. DIAMOND.

_Hyposulphite of Soda Baths._--Is there any objection to using the same
bath (saturated solution of hyposulphite) for fixing both paper calotype
_negatives_ and positives printed on albumenized paper from glass collodion
negatives?

C. E. F.

* * * * *

Replies to Minor Queries.

_Daughters taking their Mothers' Names_ (Vol. viii., p.586.).--BURIENSIS
asked for instances of temp. Edw. I., II., III., of a daughter adding to
her own name that of her mother: as Alice, daughter of Ada, &c. Though