170 W. Crookes on the War-paper Photographic Process. 
roduce @ ee similar effect to that of a bromid, butina ~ 
ion marked degree. As no particular advantage could be traced 
to it, it was not employe 4 
t ve also tried most of the different forms of organie ; 
matter, thal it is customary to add to this bath, but I cannot — 
recommend th em; the most that can be said is, that some of 
them do no harm. At first I thought a little isinglass might be — 
an improvement, as it instantly removes the greasiness from the _ 
surface of the paper, and allows the iodid of potassium to pene- 
trate more readily. Unfortunately, however, it interferes with 
the most important property of this process, that of remaining 
ime. 4 
36. I think the best results are obtained, when the jodid and 7 
bromid are mixed in the proportion of their atomic weights; the ~ 
strenzth being as follows: J 
Todid of potassium . : ; 582°5 grains, 
Bromid of potassium : .  417°5 grains. 
Dare Wate Se 40 ounces.* 
When the two salts have dissolved in the water, the mixture : 
should be filtered; the bath will then be fit for use A 
87. At first, a slight difficulty will be felt in immersing ‘the 
waxed sheets in the liquid without enclosing air bubbles, the 
the best way is to hold the paper by one end, and gradually to 
bring it down on to the liquid, commencing at the other end; 
the paper ought not to slant towards the surface of the bath, or _ 
there will be danger of enclosing air bubbles; but while it is 
being laid down, the part out of the liquid should be kept as 
nearly as possible perpendicular to the surface of the liquid; any — 
curling up of the sheet when first laid down, may be prevented 
by breathing on it gently: In about ten minutes, the sheet 
ought to be lifted up by one corner, and turned over in the sam 
manner; a slight agitation of the dish will then throw the ee 
a over that “sheet, and another can be treate c 
mann 
38. “Tho sheets must remain soaking in this bath for about 4 
three hours; several times during that interval, (and especially 
if there be many sheets in the same bath,) they ought to 
moved about and turned over singiys to allow of the liquid : 
+ While giving the above as the calculated “rt I do mt to tt q 
upon their being adhered to with any extreme accura oe . 4 
dieediiens side would I believe be without any percepti eon thea a 
