e proofs thus obtained from designs drawn with an
opaque ink, which allows a long insulation and, therefore, yields an
intense reduction, are of a deep brick-red color, quite non-actinic, and
give very good positives by the Artigues process.

N.B.--Paper in drying never assumes its original shape; it is, therefore,
necessary to make the figures on the reproductions from plans when they
are not on the originals.

CHOICE OF PAPER. SIZING.

In all the photographic processes by precipitation of metallic oxides the
quality of the paper has a great influence on the results. When the paper
is not well sized and not well calendered, the sensitizing solution is
absorbed, instead of simply impregnating the surface of the paper, and not
only the image is sunk in and its sharpness impaired, but good whites can
never be obtained, especially if the image should be toned, owing to the
impossibility of eliminating the metallic salts not acted on, that is, not
reduced by the action of light which the fibers of the paper mechanically
retain.

The "endless" rolls of paper, 54: inches wide--or "blue print paper," as it
is sometimes termed--of Blanchet freres et Kleber, of Rives, better known
as "Rives' paper", that of Johannot, of Annonay (France), and the
Steinbach (Saxe) paper are recommended.

For small prints from negatives in half tone the positive paper, 18x22
inches, of Rives or Saxe, should be preferred to the heavy kind. It is
advisable to size it, so that the impressions be entirely formed on the
surface of the paper. Moreover, an additional sizing is always
advantageous, whatever be the photographic process employed, to prevent
the imbibition of the sensitizing compound and to obtain more brilliant
and vigorous images, for the iron, chromium, uranium and other metallic
soluble salts require the presence of an organic matter (alcohol, ether,
gum arabic, glucose, caseine, etc.) to be reduced by the agency of light;
and as a consequence, the greater, within certain limits, of course, the
amount of organic matters, and the more thoroughly they are mixed with the
salts, the more sensitive the preparation and the better the results.

Arrowroot is the best sizing for our purposes. Gelatine may be employed,
albumen also, but the coating should be insolubized when applied on the
paper and dry.

_Sizing with Arrowroot._--In a porcelain dish diffuse 4 parts of powdered
arrowroot and one part of li