Edingthorpe Rectory.
_Sir W. Newton's Explanations of his Process._--In reply to MR. JOHN
STEWART'S Queries, I beg to state,
First, That I have hitherto used a paper made by Whatman in 1847, of
which I have a large quantity; it is not, however, to be procured now,
so that I do not know what paper to recommend; but I get a very good
paper at Woolley's, Holborn, opposite to Southampton Street, for
positives, at two shillings a quire, and, indeed, it might do for
negatives.
Secondly, I prefer making the iodide of silver in the way which I have
described.
Thirdly, Soft water is better for washing the iodized paper; if,
however, spring water be made use of, _warm_ water should be added, to
raise it to a temperature of sixty degrees. I think that sulphate or
bicarbonate of lime would be injurious, but I cannot speak with any
certainty in this respect, or to muriate of soda.
Fourthly, The iodized paper should keep good for a year, or longer; but
it is always safer not to make more than is likely to be used during the
season.
Fifthly, If I am going out for a day, I generally excite the paper
either the last thing the night before, or early the following morning,
and develope them the same night; but with care the paper will keep for
two or three days (if the weather is not hot) before exposure, but of
course it is always better to use it during the same day.