Photography and Potassium Cyanide: How do the Facts Compare with Fiction?

[comicsdecoder]

Greetings. You may remember me from my research on telephoto lenses for a short story I was working on several months ago. Again, cheers for all your input. (That short story has been gradually evolving into a multi-chaptered novella, incidentally.) Now I come to you photo experts with another line of inquiry that has a literary tie-in.

I’ve been working on a series of essays critiquing Laird Koenig’s 1974 novel The Little Girl Who Lives Down The Lane and the 1976 film and 1997 play based on it. In the two latter versions, the titular character poisons her mother by slipping potassium cyanide—in its original/refined powder form—into her tea. In the original novel version, however, the said poison takes the form of ‘photographic chemicals’ discovered in a study used as a darkroom by the previous owners. I was wondering, can someone provide me a brief history of the use of potassium cyanide in photography? I’m particularly interested in learning how popular the chemical was in the early to mid ’70s when the novel was written.

Thanks for the opportunity to raise such questions!

[rpcrowe]

If memory serves me correctly (and at my age, if often doesn't) Potassium Ferricyanide (I don't know the difference between ferricyanide and cyanide) was used in tintype photography as well as in some print toners. of course tintype photography was late 19th to very early 20th Century. As far as print toning, I don't know the timeframe. I began working in photography during the late 1950's and never worked with this chemical.

It was a very hazardous chemical but, a lot of what we used in the "not so good old says" was pretty darn hazardous to health of the user and to the environment.

I remember once receiving a shipment of chemicals from a decommissioned Navy Photo Lab which had several jars of potassium permanganate and of glycerine. I dropped a pair of these jars as I was unpacking the chemicals and was horrified to find out that they burst into flames as soon as the potassium permanganmate and glycerine from the broken jars were combined...

[Val Mansfield]

I remember using potassium cyanide to reduce black and white negatives that were too dark, either due to over exposure or an error in processing.

It would have been in the fifties, I would have been 11 or 12 at the time and I had to get my mother to sign the "poison book" at the local chemists. (Drug store for Americans) She wasn't totally happy about me having it, but I don't think she was concerned about me poisoning her, more about me poisoning myself.

[revi]

I think the most used was potassium ferricyanide, a salt of potassium (duh!) and a complex of cyanide and ferric ions ([Fe(CN)₆]^-3).
Ferricyanide in itself is not that dangerous if handled properly, but can liberate cyanide gas (HCN) under certain conditions. The latter is highly toxic.

The ferricyanide (a.k.a. hexacyanoferrate(III)) was commonly used in Farmer's solution to 'bleach' B/W photos and negatives.

(see here for the wikipedia entry).

To get back to the OP's question:
I have used the ferricyanide (in Farmer's reducer) in the 70's,and iirc it was considered more or less a standard tool. I don't remember mentions of using cyanide in photography.
I have to add that that was the era where ferricyanide, potassium permanganate and such were sold in chemistry kits for kids

[Shadowman]

You should get a fact checker for your novel, any chemistry major forced to take a literature course will eat you up on their essay.

[MiniChris]

Potassium Ferricyanide is the primary ingredient to the process known as Cyanotype. Other than staining your hands a tad to the blue side, it is pretty harmless. However, any cyanide without a binder or kicker will be an exceptionally fast killer...

"what makes cyanide so notorious is the speed that it acts. Cyanides are amoungst the most fast acting poisons known, mainly sodium cyanide and potassium cyanide as well as hydrogen cyanide."

.2 grams is quite a sufficient lethal dose, an amount easily slipped into a cup of tea - though, just as easily traceable.

[krispix]

I remember using potassium cyanide to reduce black and white negatives that were too dark, either due to over exposure or an error in processing.

It would have been in the fifties, I would have been 11 or 12 at the time and I had to get my mother to sign the "poison book" at the local chemists. (Drug store for Americans) She wasn't totally happy about me having it, but I don't think she was concerned about me poisoning her, more about me poisoning myself.

Hi Val,
I think, if you search your memory banks, you'll find that it was Potassium Ferricyanide that you were using. Commonly called Farmer's Reducer. This works by partially reducing the metallic silver image (the black bits) back to the original silver metal halide (emulsion) which you then dissolve away in a fixing bath. I seem to recall that in extreme cases you could dissolve a few crystals in a standard acid fixing solution - This had a very short working life and required the negative to be thoroughly washed afterwards to avoid staining.
I'm afraid that even in the 50's they would not have sold Potassium Cyanide to you, with or without your Mum's signature unless you worked for the US penal system and wanted it for the Gas Chamber on Death Row.

[comicsdecoder]

Once again, I'm impressed with the received responses.

As I suspected, it appears that any photographic chemicals containing or related to potassium cyanide had dropped out of common usage by the early '70s when Mr Koenig was writing his novel. As well, from what I can gather, potassium ferricyanide would have only proved dangerous or deadly under particular conditions. This probably explains why Mr Koenig altered the poisoning details in the screenplay version of his novel just two years later--someone must have brought him up to speed on the ins and outs of modern photography.

Cheers for all the input, people. When I publish this series of essays as a Kindle book in the weeks ahead, I'll make sure to give the Cambridge In Colour brain trust a credit in the Thanks department. And if there's any other insight into this matter, please share your knowledge. It will be much appreciated.