What was/is Meritol?

[Jerevan]

I was looking in a photographic book today, and found some chemistry recipes, one of which included Meritol. The book was reprinted in 1947, just to give a clue to its age.

I did a google on that name and came up with hexahydric alcohol, chemical name C6H14O6 and CAS 50-70-4. It seems more commonly known as Sorbitol.

Could it be this (sounds strange) or was Meritol a proprietary chemical substance?

[Nick Zentena]

The formula in my book is:

C6H4(OH)2: C6H4(NH2)2 =218

Patented by Johnson and Sons LTD. No date given.

Fine grain developer

[Seele]

According to The Focal Encyclopaedia of Photography, Meritol has the formula of C6H4(OH)2.C6H4(NH2)2, molecular weight 218.

Meritol was a proprietary developing agent made by Johnsons.

[Jerevan]

Thank you very much,

judging from that formula, it seems to be composed of catechol and possibly o-phenylenediamine. But I am no chemist, as you already have understood by now, just curious by nature.

The formula consists of Metol, Meritol, Sodium Sulphite and water. And in the book it's called Johnsons Meritol-Metol, for obvoius reasons...

[Helen B]

I mentioned it in the recipe for MCM100 in the recipes section here:

"Meritol was a proprietary Johnson developing agent, a compound of p-Phenylenediamine (PPD) and catechol. The 16 g of Meritol can be replaced with 7 g of PPD and 9 g of catechol."

The book wouldn't happen to be Jacobson's Developing would it?

Best,
Helen

[Jordan]

One of the problems with organic chemistry is that the structural formulas often don't mean much. C6H4(OH)2 could conceivably represent either hydroquinone, catechol (both photochemically active) or resorcinol (not photochemically active), the three isomers of dihydroxybenzene. Similarly, there are a few isomers of phenylenediamine that could be represented by C6H4(NH2)2.

Since it's used photographically, my guess is that Meritol is probably some kind of co-crystal of para-phenylenediamine with either hydroquinone or catechol.

[Jordan]

I simulposted with Helen, I guess. Still, it's nice to know I was on the right track.

[Jerevan]

Thanks for the clarifications - now I know what I am looking at... wasn't sure if it was o-, m- or p-phenylenediamine.

No, the book is actually "Photography by Artificial Light" by Marcel Natkin who also wrote the book "Photography without Tears".

I might as well give the whole of the recipe and it is as follows, verbatim apart from the left out avoirdupois quantities:

[FONT=Courier New]Metol - 2.3 grammes
Meritol - 13.7 grammes
Sodium Sulphite (crystals) 90 grammes
or
Sodium Sulphite (anhydrous) 45 grammes
Water up to - 1 litre

Dissolve the chemicals in the order given.
Develop for about 12 minutes at 65 F or 18 C for fast films.
1 litre will develop from 8 to 10, 36 exp. 35 mm. films. [/FONT]

What constituted fast films in 1947 is probably something like ISO 160-200 today, I suppose. According to the text, extremely fine grain is obtainable with this formula.

[piticu]

No, the book is actually "Photography by Artificial Light" by Marcel Natkin

Metol - 2.3 grammes
Meritol - 13.7 grammes
Sodium Sulphite (crystals) 90 grammes
or
Sodium Sulphite (anhydrous) 45 grammes
Water up to - 1 litre

Dissolve the chemicals in the order given.
Develop for about 12 minutes at 65 F or 18 C for fast films.
1 litre will develop from 8 to 10, 36 exp. 35 mm. films.

Do you mind digging the book out and check the page no that formula is on? Or scan the page if it's not too much to ask?
I need that info for a small project i'm working on. http://bwformula.atelierelealbe.eu/index.php/JJ97
Thanks

[Ian Grant]

Here's the complete list of Meritol formulae that Johnsons published

MCM100 was devised by a column writer for Miniature Camera Magazine just before WWII, apart from being a keen photographer and writer he was also the advertising agent for both Ilford & Johnsons so had strong ties with the photographic industry.

Johnsons is the oldest of all photographic companies still trading (as Johnsons Photopia), they supplied Silver Nitrate ect to Fox Talbot, although they closed their chemistry division in the early 1970's.

Ian