458 On Sun Pictures. 
oyer the paper, the line of the sky is clearly marked and 
begins to darken, and the trees which cut it remain white— 
the buildings begin to appear: the operator watches them 
attentively as they seem to grow out of the paper. What is 
that ?—a large part of the picture still retains its original 
whiteness. He cannot make it out; he applies more Gallic 
acid without any improvement, the white blot still remains ; 
and the disappointed operator is at last obliged to acknow- 
ledge with regret that his negative is a failure. The most 
frequent cause of these disagreeable failures is, I think, the 
presence of organic matter in the water used in the first 
operation, which cannot always be obtained quite pure. 
Newly-caught rain water or spring water, not too hard, are 
the best. 
Other causes of failure are the following. The paper may 
not be evenly or well made, the size upon it may not be pure, 
the paper may have been touched by dirty fingers; the 
chemicals may have been spoilt by the voyage from England, 
may not be pure, or may not be evenly spread upon the 
paper. 
Many trials and the greatest care are requisite to, produce 
even moderately good impressions. When, however, really 
good negatives of interesting subjects are obtained, they are 
truly valuable; as with care an unlimited number of copies 
may be procured from them, each slightly varying in tint 
from a rich brown to jet black. 
Tf successful, the enthusiastic photographist feels that 
his labour is repaid, since he possesses the power of making 
copies from nature which in tint rival sketches produced 
in sepia and Indian ink, and surpass them in accuracy 
and minuteness. ‘The labour of several days must be 
applied te the production of sketches by the hand such as 
