communicated
this singular result; and to this process or class of processes (which
I cannot doubt when pursued will lead to some very beautiful results,)
I propose to restrict the name in question, though it applies even more
appropriately to the following exceedingly curious and remarkable one,
in which silver is concerned:

At the last meeting I announced a mode of producing, by means of a
solution of silver, in conjunction with ferro-tartaric acid, a dormant
picture brought into a forcible negative impression by the breath or
moist air. (See Cyanotype.) The solution then described, and which had
at that time been prepared some weeks, I may here incidentally remark,
has retained its limpidity and photogenic properties, quite unimpaired
during the whole year since elapsed, and is now as sensitive as
ever,--a property of no small value. Now, when a picture (for example
an impression from an engraving) is taken on paper washed with this
solution, it shows no sign of a picture on its back, whether that on
its face is developed or not; but if, while the actinic influence is
still fresh upon the face, (i.e., as soon as it is removed from the
light), the back be exposed for a very few seconds to the sunshine, and
then removed to a gloomy place, a positive picture, the exact
complement of the negative one on the other side, though wanting of
course in sharpness if the paper be thick, slowly and gradually makes
its appearance there, and in half an hour or an hour acquires a
considerable intensity. I ought to mention that the "ferro-tartaric
acid" in question is prepared by precipitating the ferro-tartrate of
ammonia (ammonia-tartrate of iron) by acetate of lead, and decomposing
the precipitate by dilute sulphuric acid. When lead is used in the
preparation of Amphitype paper, the parts upon which the light has
acted are found to be in a very high degree rendered water proof.--Sir
J. Herschel.

This process is a new invention of our countryman, J. A. Whipple, Esq.,
of Boston, and has been patented by M. A. Root, Esq., of Philadelphia.
It will be seen, however, from the previous pages of my work that Mr.
Root is mistaken in regard to his being the first improvement patented
in this country, although it is unquestionably the first by an
American. Of this improvement Mr. Root says:

VI. "CRAYON DAGUERREOTYPE."

"The improvement to which you refer is denominated "The Crayon
Daguerreotype." This invention made by Mr. J