Photography is a matter of Taste: a lesson by Sir John Herschel

PVia said:

This is a little off-thread, but is probably the best place to include it.

Someone very close to me is ill with cancer that is being treated via hepatic infusion with the drug, cisplatin(um). During recovery immediately after the infusion, an IV of 25% sodium thiosulfate is given. You can imagine my surprise when I saw the label. It supposedly has a chelation effect on the body in helping to rid it of heavy metals, in this case, platinum, and thereby reduce side effects. The doctor was interested in hearing about its use in photography as well.

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Sodium thiosulfate, along with sodium nitrite, is also part of the treatment for cyanide poisoning. So I guess if you accidentally ingest some KCN in the darkroom, you should inject yourself with fixer ASAP!

Photo Engineer said:

There is no difference in odor and the odor is due to Benzaldehyde.

PE

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But then why do people talk of the "smell of bitter almonds" while they could also be saying "smell of sweet almonds" if there is no difference in odor?

Michel;

Ask them then not me. I guess I don't know. Here the bottles are just labeled Oil of Almond.

PE

The aroma of Extracted oils are not due to single compounds, but are usually the result of a principal component that is affected by the presence of the other components.
Esters, aldehydes, alcohols lots of stuff.

Ray;

I think that you will find that Benzaldehyde and Cinnamaldehyde are "pure" flavorings for almond and cinnamon respectively so what you state is not always true. Apples, Pears and other fruits are indeed combinations, but some are pure substances and are sold as such.

PE

Great find!

For those of you less proficient with computers, I have included below the direct link to the PDF file of The Edinburgh Philosophical Journal of 1819 containing Herschel's article:

The Edinburgh Philosophical Journal of 1819:
http://ia600400.us.archive.org/6/items/edinburghphilos05edingoog/edinburghphilos05edingoog.pdf

Doremus Scudder said:

Okay, I'll bite and ask the stupid question that this thread begs:

Can one (and would it be safe to) test modern fixers with Herschel's taste test?

I rather doubt it, but I'd love to hear from the experts (PE?)

Best,

Doremus Scudder

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Michel Hardy-Vallée said:

I do not recommend tasting fixer either, since we have all sorts of other, safer ways to deal with chemicals. In Herschel's days, the body was still one of the best detector they had.

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Well, whatever became of him, in 1940 some photography chemists still couldn't resist the lure of their products, and found it a "matter of taste"

Still from the "The Alchemist in Hollywood". This chemist seems to thoroughly enjoy his sip of hydroquinone developer... :



I also remember a scene from a documentary movie where a person tastes photopaper (before and after using fixer?), noticing a salty taste from the silverhalides. I thought it was a scene from the same "Alchemist in Hollywood" video, but reviewing the entire video, I didn't find it. If someone else remembers it, and knows the source, post it here in the thread!

Photo Engineer said:

Unfortunately, you can use old hypo as no-cal sweetener, but only once. You probably would not survive. (just kidding but it will make you very ill, especially those containing Ammonia - enough could kill)

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Of course, since the old style fixers contained sodium instead of ammonia, the problem was probably less, and tasting it a minor risk.

For those of you interested in the history of photography and the chemistry behind it, I can highly recommend viewing the following two parts of the "The Alchemist in Hollywood" video on YouTube:

[video=youtube;sG5nSDcvSzE]http://www.youtube.com/watch?v=sG5nSDcvSzE[/video]

[video=youtube;Vpx15qNOOSg]http://www.youtube.com/watch?v=Vpx15qNOOSg[/video]

Marco

Thanks for posting the vid Marco.

Thanks Marco, I'll check these out!

Photo Engineer said:

Acid mixed with Potassium Ferricyanide does NOT release the Cyanide gas. It requires much stronger treatment to get HCN from Ferricyanide.

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I have to disagree somewhat with the previous statements as I routinely release cyanide gas from ferricyanide with acid solutions when testing for cyanide. It is too general in it's claims.

A 5% solution of sulfuric acid is sufficient to release cyanide from ferricyanide when testing for "total cyanide" by EPA methods. Note that it does take strong acids to release the cyanide from the ferricyanide complex and heat does help - although there are other cyanide-metal complexes (such as cobalt) that will not liberate cyanide even by this method.

Weak acids, like acetic, are not strong enough to release cyanide from complexes like ferricyanide - they will only liberate cyanide from "simple" cyanides (like salts with say potassium or sodium) or "free" cyanide (that is, cyanic acid solutions).

All that said, there is little chance of releasing cyanide from ferricyanide in the home darkroom. Keep it away from strong acids like sulfuric and it is complexly safe from cyanide release.

Kirk the cyanide analyst for the last 20 years...

Physicians, like chemists have for centuries relied on taste to help identification of disease. Diabetes Mellitus and Diabetes Insipidus (from their names) were distinguished in a person with Polydipsia, Polyuria and wasting by the simple method of tasting the urine. Sugar in one and none in the other. Death anyway.

My wife worked as a lab tech back when and in the whole lab she was the only one who could smell the cyanide compounds across the room when it was being used. Darwinian, perhaps?

Wasn't the first cyanide murder done by distilling cherry pits to get the cyanide salts? More useless information I learned in pathology.

Photo Engineer said:

Ray;

I think that you will find that Benzaldehyde and Cinnamaldehyde are "pure" flavorings for almond and cinnamon respectively so what you state is not always true. PE

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Not at all.

The fact that unscrupulous people/companies think they can get away with fooling the average consumer does not make for good science!

What you described is simply the trueism that sometimes one particular compound is prominate... and/or can be readily associated with a flavor that is well known.

What I said (or tried to say) was that essential oils are not single pure chemicals.
OK, there may be exceptions - there usually are.

But Cinnamon is not one of them.
The fact that someone might sell Cinnamaldehyde as cinnamon flavor or "cinnamon oil" does not negate the fact that it is not, in the true sense, the essential oil of cinnamon.

In the trade, several varieties are actually recogonized.
And, there are varieties that are necessarialy traded,
but are nevertheless both "cinnamon" and different.

Even Wikipedia clearly states that only about 60-90% of the essential oil of cinnamon is Cinnamaldehyde... and when you consider that essential oils are only "essential" when associated with specific trees, and you realise there are several trees which can (and are) used to make what the general public calls "cinnamon", (I like Saigon Cinnamon myself) well, I think you get the picture.

Sorry,
Cinnamaldehyde is NOT the essential oil of cinnamon;
at best, it is mearly the major component.

OTOH
IT may be sold on some markets as a "pure" flavoring.

But this is Apples and Oranges.

Kirk Keyes said:

I have to disagree somewhat with the previous statements as I routinely release cyanide gas from ferricyanide with acid solutions when testing for cyanide. It is too general in it's claims.

Kirk the cyanide analyst for the last 20 years...

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This is good to know. I have sulfuric acid at 48% and farmer's reducer sitting in the same box. The chances of something happening are slim, but I'd rather know more than less!

Thanks

Kirk is correct. Our findings were that strong acid and heat would release cyanide gas, but cool dilute acid would not. We had to prove that acidic effluent would not release cyanide gas for the benefit of the EPA. It only proves that you must know what you are doing when you work with chemicals that are potentially deadly..

My statement was too much of a generalization.

http://en.wikipedia.org/wiki/Potassium_ferricyanide

PE

Ray;

Without Benzaldehyde, the remaining oils in Almond flavoring would be tasteless and useless and without Cinnamaldehyde, that flavoring would also be useless. They are the essential ingredients that impart the primary flavor, and that is the sens of my meaning. They also supply the major part of the odor. And, they can be used alone to give the sensory response of the mix which can be obtained only from natural products. And so, it depends on what you want.

BTW, pressing Cinnamon bark gives the truest mix, whereas steam distillation, used by many, gives mainly the aldehyde. That also enters into what you get in a given flavoring. The method of production is important with respect to the ratios of the ingredients.

PE

Murray Kelly said:

My wife worked as a lab tech back when and in the whole lab she was the only one who could smell the cyanide compounds across the room when it was being used. Darwinian, perhaps?

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That must have been a lot of cyanide!

Myself, I find that when I sniff the air in the 1 kg bottle of Potassium Cyanide I have at work I get a sensation of HCl mixed with a light hint of stinky feet.

I guess I need to go find some bitter almonds, but I do not find that cyanide gas smells much like regular almonds.

Movie Spoiler coming:
There's a great movie starring Jodie Foster (at about age 14) and Martin Sheen. Jodie plays the smart girl that's rasing herself after the death of her father, and Martin Sheen plays the creepy neighbor that has figured out that Jodie is home alone. Eventually, he blackmails her and lets her know she needs to give into his bad intentions, and she pretends that she will, as she hands him a cup of tea and a plate of almond cookies. When she leaves the room to get something, he switches the teacups, taking hers for himself, which is laced with cyanide. He comments on the almond scent, she replies it must be the cookies as he begins to choke and gasp for air...

Great Movie - it's called "The Little Girl Who Lives Down the Lane".