80 THE NORTHERN MICROSCOPIST. 
Hy ebanliiies Of OUR tA veep es ext ss eee 4 ounces. 
Watters esi et eee eee es a ois ae te ee 20 s 
In cases where, from unavoidable over-exposure, it has been 
impossible to obtain density with the alkaline developer, a most 
careful washing should be given after fixing, with a view to remove 
the last trace of the alkali (ammonia). 
Intensification can then be effected with acid pyro. and nitrate of 
silver, or with protosulphate of iron and nitrate of silver. We havea 
decided preference for the latter, and use the following formula, viz. : 
A. 
Protostlphateé Of ION 3.2 .csse0cs+2sess0s2enenee een 15 grains. 
Gelatino Acetic Acid Solution (as described below).40 drops. 
WAKE eis. neinecdcerdnaeacwerqntscoes+a¢enss sees een I ounce, 
B. 
Nitrate of Silver. ........2000.2+.s0s00s0s<s aspen 10 grains. 
Acetic Acid, Glacial, 50°......,...0::2s.0sese eee ro drops. 
WALED is oie ce isea cas asanedbesnaass nage ae ae enee enn T ounce. 
The Gelatino Acetic Acid Solution is compounded as under :— 
Gelatines.)..i.i.is.c5sasdcerecseess acces joveneeen I5 grains. 
Acetic Acid, Glacial, (50°. :....-..+..«salsseaseaeeaanee 3 drachms. 
WALEE.. ..520c1ecosenagscavedgsearcy us ts cctee eee : 
and it is well to prepare a stock of this, and also of “A,” as ‘they 
are both better for keeping. 
To proceed : first flood the plate with water, and then with a 
solution of iodine and iodide of potassium of the colour of pale 
sherry for one minute ; rinse it off, and apply enough of “A” to 
cover the plate for about the same time. Now drop into the cup 
a drachm of “ B,” and bring “ A” back from the plate to the cup 
to mix them together. Re-apply, and keep moving over the sur- 
face until density is sufficient. If any air-bells should occur they 
must be kept moving, and then they will do no harm. 
Both development and intensification are best performed in a 
dish ; the former in ebonite, the latter in porcelain. 
When the plate has again become dry, warm and varnish it as 
usual. 
Having obtained a suitable negative it is easy to print from this 
either upon carbon tissue or the ordinary sensitive paper, which 
may now be bought prepared, at one shilling per sheet. It will 
keep in good condition for months. 
After printing several shades darker than is finally required, the 
prints are soaked in water to remove the free nitrate of silver, and 
then put to tone in the following bath :— 
Chioride of Golde as aun, 6 ae « suena eae 15 grains. 
Acetate Of Sodale. 5am seasvirvesk. PP Lys S I ounce. 
WV QECL 55 i9, sn genaeaees ee hs epegnaceas eee ...80 ounces, 
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