A Manual Of Photography

MB. PONTON’S PBOCESS. white upon an orange ground, and quite planent. If exposed for many hours together to strong sunshine i he colour .,1 the ground is apt to lose in depth, but not more “^^mte of colouring matters. This action of hg i 011 , ^ the potash differs from that upon the salts of siver. T™ latter which are blackened by light are of themselv es insolub in water, and it is difficult to impregnate paper with them in a uniform manner. The blackening seems to be caused by the mation of oxide of silver., -.inex- “ In the case of the bichromate of potash, again, that salt is ex ceedingly soluble, and paper can be easily àtàithà The agency of light not only « Ä SuM s mode of ^o^on^fthat salt ; soak the paper well 111 it, and then green. In this way, also, the object may be represented darker shade than the ground.,, fhnmrh as sen- much inferior to most of them, and is no . - ^e well for the camera obscura. This paper, however, for taking drawings from dried plants, or fo:1 5°!^ with great recommendation is its elieapness, an of notash which it can be prepared. The price o he dàmàof làh is about two shillings per pound, whilst the n shillings the ounce. pictures prevents the per- As the deep orange ground of these p easy to procure my number of facshndes of an engraving, by transfer from the any number The correct copies have a beautiful first negative pho g 1 managed, but little of the minute sharpness; and, if carefully manageu, u detail of the ^^phot0graphic paper prepared with the Mdescribed byVE. Becquerel. He states,-It is sufficient to steep a paper prepared in Mr.