Of the different developing tanks manufactured for professional use, we describe a few. Each tank is constructed with the intention of overcoming the usual difficulties met with in tank developing, which are, principally, retaining of even temperature during development, the overcoming of streaks, uneven developing of the plate, and also the prevention of air-bells.

The Burke & James Style C Tank. - With this style of tank, if desired, the plates may be developed and fixed in the same tank. The exposed plates are put into the plate rack, which, in turn, is placed into an inner tank. This part is done in the dark-room. The cover being securely fastened, the light may be turned on, the door of the darkroom may be opened, or the tank may even be brought into broad daylight. The inner tank is then lowered into the outer tank containing the developing solution, and left for half the developing period, when the inner tank is withdrawn and reversed. The reversing of the plates insures uniformity of development.

A light-tight opening in the bottom of the inner tank admits the developer, and an opening at the top allows the air to escape, permitting the tank to fill rapidly. The tank being made of brass, nickel-plated, it can, if desired, be used for fixing as well as developing. (See Illustration No. 21.)

Eagle Developing Tank. - The Eagle Adjustable Tank is made in two styles, zinc and nickel-plated. The zinc is intended for developing only, as the fixing bath would be affected by the zinc. The nickel-plated tank can be used for developing, fixing and washing.

The plates are loaded in the rack and then placed in the tank containing the solution, the cover being placed on the tank, and the plates are then on their way developing. As the cover fits tightly the tank can be turned upside down a few times during developing, thus insuring even development. When the plates are developed they may be removed to the regular fixing tank; or, if the nickel-plated tank is used, and when so desired, the developer may be poured off and sufficient hypo solution (hypo, 1 oz., water, 4 ozs.) to cover the plates poured in. When properly fixed, pour off the fixing solution and wash the plates by allowing the water from the tap to flow through the funnel. This method removes the hypo from both plates and tank at the same time.

Illustration No. 21. B. & J. Developing Tank. Style C. See Page No 224f

Illustration No. 21. B. & J. Developing Tank. Style C. See Page No 224f.

Illustration No. 22. Eagle Developing Tank See Page 224i.

Illustration No. 22. Eagle Developing Tank See Page 224i..

Illustration No. 23. Eagle Developing Tank See Page 224.

Illustration No. 23. Eagle Developing Tank See Page 224..

Illustration No. 24. Lowering Rack of Plates Into Solution Cup.

Illustration No. 24. Lowering Rack of Plates Into Solution Cup..

See Page No. 2242.

Illustration No. 25. Loading Plate Into Rack. See Page 224i.

Illustration No. 25. Loading Plate Into Rack. See Page 224i..

Eastman Developing Tank.

The professional sizes of these tanks are known as the Nos. 11 and 12. The No. 11 will hold 48 5x7 size, or smaller; the No. 12 will hold 24 8x10 size, or smaller. The professional sizes are made with a handle, which, when the rack is lifted partly out of the tank, falls over the side and locks, holding the rack up out of the developer. (See Illustrations Nos. 22 and 23.

Eastman Plate Tank. - The Eastman developing tank is made in different sizes to accommodate all of the standard sizes of plates. Those recommended for the professional are the 5x7 and 8 x 10 sizes. In Volume I of this library we fully illustrate the use of the smaller size tank. The 5x7 tank is manipulated in practically the same way, although it is slightly different in construction, and is fitted with a cage for holding twelve 5x7 plates, and requires 64 ounces of solution. (See Illustrations Nos. 24 and 25.) The 8 x 10 tank has an adjustable metal cage for the holding of plates from 41/4 x 6 1/2 to 8 x 10, and requires 156 ozs. of solution. (See Illustrations Nos. 26 and 27.)

Developing Formulae. - The following Pyro or Glycin formulae will produce good results:

Pyro Formula For Tank Developing

A

Water......................

16 ozs.

Pyro .......................

1 oz.

Oxalic Acid

10 grs.

B

Water........................

16 ozs.

Eastman's Sulphite of Soda....

3 ozs.

C

Water........................

16 ozs.

Eastman's Carbonate of Soda..

1 oz.

For 5x7 tank use-

A ............................

1 oz.

B ............................

1 oz.

C.............................

1 oz.

Water

61 ozs.

For 8x10 tank use-

A

2 1/2 ozs.

B .............................

2 1/2 ozs.

C ............................

2 1/2 ozs.

Water........................

To Make up 156 ozs.

Note. - If crystal sodas are used take three times the quantity of carbonate and double the quantity of sulphite. With the temperature at 65° Fahr. this formula will develop plates completely in 30 minutes. With the temperature at 70° Fahr. the plates will be fully developed in 25 minutes.

Glycin Tank Developer

Stock Solution.

Hot water,about 200

60 ozs.

Carbonate of Soda (Eastman's) ..

2 ozs.

Glycin

1/2 oz.

Sulphite of Soda (Eastman's)....

............. 1/2 oz.

Dissolve in the order given.

For the 5x7 tank use -

Stock Solution

6 ozs.

Water..........................

58 ozs.

For the 8x10 tank use -

Styock solution

15 ozs.

Water..........................

141 ozs.

With the temperature at 65° Fahr. this developer will completely develop plates in 30 minutes.

Fixing Bath Recommended

By Weight.

A

Water ..............

.96 ozs.

Sulphite of Soda.....

. 2 OZS.

Hypo ...............

. 2 lbs.

' B .

Water..............

.32 ozs.

Chrome Alum

. 2 OZS.

Sulphuric Acid C. P..

1/4 oz.

By Hydrometer.

A

Hypo, Test 80.......

100 ozs.

Sulphite of Soda, Test 60...........

16 ozs.

B

Chrome Alum, Test 20...........

32 ozs.

Sulphuric Acid C. P

. 2 dms

Illustration No. 26. Placing Septum over Lower Tier of Plates. See Page No. 224i.

Illustration No. 26. Placing Septum over Lower Tier of Plates. See Page No. 224i..

Illustration No. 27. Fastening Cover of Solution Cup.

Illustration No. 27. Fastening Cover of Solution Cup..

See Page No. 224i.

Eastman Developing Tank.

Tank Developing for the Professional.

224m

When dissolved pour B into A, slowly, while stirring A rapidly. This bath may be used continuously so long as it fixes plates in 15 minutes' time.