486 
frame and upon it a fresh sheet of the «‘ Aristo”’ paper is laid and 
clamped in place. The printing of the positive in the full\sun- 
light is the work of only a half minute or so, but better results 
‘ are often obtained by a slower printing in diffused light; in fact 
the same rules hold good for this form of printing as for that of 
ordinary negatives taken by means of the camera. 
The process of toning is the same for the positive as the nega- 
tive, and in the same bath an indefinite number of either or both 
may be undergoing the process at the same time. 
The fact that the object needs to be partially translucent 
places limitations upon the application of the process, as likewise 
does the inability to enlarge or reduce the size of the object. 
There are, however, very many instances when the process may 
be employed with a considerable degree of satisfaction, and in 
some cases it is possible to bring out points of structure not re- 
corded by the ordinary methods of photography. The principle 
is different, for in the one reflected light is ordinarily employed 
and a surface picture only is obtained; but by the Solandi (Sol 
and I) process the picture is obtained by the unequal transmission 
of light through the different parts of the object. For example 
a leaf variegation may be confined to the surface cells and is 
easily caught by photography, but not in the sun print. On the 
other hand the variegation may be more than skin deep and the 
results may be reversed by the two methods. Any object that is 
naturally thin enough to permit the passage of light, even feebly, 
may become a subject for sun printing, the time of exposure © 
being correspondingly increased. Thick leaves like the orange, 
through which but little light seems to pass will give good prints 
after an exposure of a few hours, while ordinary leaves, as those 
ot the maple, are quickly done. The orange leaf is a case in point — a 
where the sun print reveals in a striking manner the number, size, 
position, etc., of the oil glands, all of which are not secured in the 
common photograph. Anything like the venation of leaves is of 
course secured’ with full details by the process of transmitted 
light. In like manner many good records can be made of the — 
various rusts, leaf spots and blights upon foliage, and excellent = 
pictures of wood are secured when thin sections in any direchion 
of ied gain are employed. 
