Chondrule
Active member
I purchased some vintage electrical components to salvage the platinum parts, I had never done this before so wasn't sure what to expect. Turns out, the parts I expected to be platinum actually were platinum, so no surprise there, but what I didn't expect was that some of the other parts were gold.
The gold parts were tips (electrical contacts) at the ends of brass pins which were about an 1/8" in diameter, so I cut these off as short as possible and dissolved them in straight nitric. So far so good, I was left with 2 grams of gold tips in intact condition, which isn't much, but actually it is when it's considered that this gold was unexpected bonus material.
Just to be clear, these gold tips/contacts were manufactured separately from the brass pins they were attached to, they were manufactured separately and then added onto the brass pins, thus when dissolved in the nitric there was a complete separation of the two. All I'm saying here is that the brass pins were not plated with the gold.
So I dissolved these tips in AR. I like to overdo it with the hydrochloric and under do it with the nitric. The tips weighing in at a mere 2 grams, I used 10ml of hydrochloric and started the reaction with 1ml of nitric. Before long the reaction slowed so an additional 1ml of nitric was added, which again got the red fumes started and I knew that more gold was being attacked.
After the addition of the second dose of nitric, shortly thereafter the red fumes subsided yet I had considerable metal left to be dissolved, only about 1/3 of the metal had gone into solution, which didn't make sense since the 2ml total of nitric should've been sufficient to nearly dissolve all my material. So I added 1/2ml of nitric and got no further reaction, this told me it was time to quit, all the gold that was possibly going to dissolve had done so.
So it became obvious that these tips were plated with a thick layer of gold, the question became what was the core material, I figured it was silver since the AR had no effect on them. I rinsed these cores and then heated them to red hot with a torch. The following image is of a few of these cores as they stand now.
Setting the cores aside and focusing on the AR, knowing that I had overdone it with the nitric, I evaporated till the solution turned into crystals at the bottom of the beaker, then added hydrochloric and repeated this crystallization. After killing the nitric twice, I again added the hydrochloric and a couple drops of sulfuric, then filtered the solution and dropped the gold using SMB. The following image is of the precipitated gold and leftover solution after settling, this solution does have that slight residual coloration to it as shown in the image, not the crystal clear that I normally get when precipitating gold.
Using fresh stannous only a few days old, I checked the solution to be sure that all gold had precipitated, which typically it always is in my case since I always overdo it with the SMB. Sure enough, the stannous test proved negative for gold, but what I didn't expect was the brilliant orange result that I got instead, see the following image.
The brilliant orange was an instantaneous result, after about 10 minutes the color had changed more towards brown, see the following image.
Never having had the pleasure of working with platinum in solution, thus never having seen a stannous test of a platinum bearing solution, I need to ask if this is what I'm looking at? Whatever the stannous test is indicating, it sure seems as if whatever is in solution is strong, the test doesn't look to be saying a mere trace of something is in solution, it seems to be saying there's a lot of it.
Unless you gentlemen suggest otherwise, what I'm thinking of doing next is seeing what will precipitate using ammonium chloride. When dissolving the gold in AR, and having noticed that the reaction had ceased, I did continue with the heat for almost an hour, what I'm getting at here is that if these cores are in fact platinum, possibly enough did get into solution that enough could be precipitated with the ammonium chloride.
Or have another idea, I could hit these cores with straight nitric and see if they dissolve, if so then I'll know they're not platinum and are probably the silver that I initially suspected. If the nitric has no effect, I can then add hydrochloric and return to attacking them with AR, this time however continuing the process for much longer than the hour I had subjected them to before, for platinum should take way longer.
By the way, referring back to the image of the cores on the Q-tip, notice that the few cores shown are stuck together with some sort of a transparent, black tinted, sort of shellac, this was the result of heating them to red hot. These cores are not stuck together because of partial melting, the shellac like substance that accumulated on the surfaces is definitely the culprit. Not sure what this is all about, it's as if something came out of the metal, such as how silicone comes out of bronze bushings that are impregnated with that stuff. For all I know, maybe these cores are palladium and this is how that metal reacts when heated, but just as with platinum, I've not ever messed with palladium either, so I'll wait to here from you guys, hopefully one of you will recognize what's going on here.
Anyway, let me know what you gentlemen think, thanks.
So let me know what you gentlemen think.
The gold parts were tips (electrical contacts) at the ends of brass pins which were about an 1/8" in diameter, so I cut these off as short as possible and dissolved them in straight nitric. So far so good, I was left with 2 grams of gold tips in intact condition, which isn't much, but actually it is when it's considered that this gold was unexpected bonus material.
Just to be clear, these gold tips/contacts were manufactured separately from the brass pins they were attached to, they were manufactured separately and then added onto the brass pins, thus when dissolved in the nitric there was a complete separation of the two. All I'm saying here is that the brass pins were not plated with the gold.
So I dissolved these tips in AR. I like to overdo it with the hydrochloric and under do it with the nitric. The tips weighing in at a mere 2 grams, I used 10ml of hydrochloric and started the reaction with 1ml of nitric. Before long the reaction slowed so an additional 1ml of nitric was added, which again got the red fumes started and I knew that more gold was being attacked.
After the addition of the second dose of nitric, shortly thereafter the red fumes subsided yet I had considerable metal left to be dissolved, only about 1/3 of the metal had gone into solution, which didn't make sense since the 2ml total of nitric should've been sufficient to nearly dissolve all my material. So I added 1/2ml of nitric and got no further reaction, this told me it was time to quit, all the gold that was possibly going to dissolve had done so.
So it became obvious that these tips were plated with a thick layer of gold, the question became what was the core material, I figured it was silver since the AR had no effect on them. I rinsed these cores and then heated them to red hot with a torch. The following image is of a few of these cores as they stand now.
Setting the cores aside and focusing on the AR, knowing that I had overdone it with the nitric, I evaporated till the solution turned into crystals at the bottom of the beaker, then added hydrochloric and repeated this crystallization. After killing the nitric twice, I again added the hydrochloric and a couple drops of sulfuric, then filtered the solution and dropped the gold using SMB. The following image is of the precipitated gold and leftover solution after settling, this solution does have that slight residual coloration to it as shown in the image, not the crystal clear that I normally get when precipitating gold.
Using fresh stannous only a few days old, I checked the solution to be sure that all gold had precipitated, which typically it always is in my case since I always overdo it with the SMB. Sure enough, the stannous test proved negative for gold, but what I didn't expect was the brilliant orange result that I got instead, see the following image.
The brilliant orange was an instantaneous result, after about 10 minutes the color had changed more towards brown, see the following image.
Never having had the pleasure of working with platinum in solution, thus never having seen a stannous test of a platinum bearing solution, I need to ask if this is what I'm looking at? Whatever the stannous test is indicating, it sure seems as if whatever is in solution is strong, the test doesn't look to be saying a mere trace of something is in solution, it seems to be saying there's a lot of it.
Unless you gentlemen suggest otherwise, what I'm thinking of doing next is seeing what will precipitate using ammonium chloride. When dissolving the gold in AR, and having noticed that the reaction had ceased, I did continue with the heat for almost an hour, what I'm getting at here is that if these cores are in fact platinum, possibly enough did get into solution that enough could be precipitated with the ammonium chloride.
Or have another idea, I could hit these cores with straight nitric and see if they dissolve, if so then I'll know they're not platinum and are probably the silver that I initially suspected. If the nitric has no effect, I can then add hydrochloric and return to attacking them with AR, this time however continuing the process for much longer than the hour I had subjected them to before, for platinum should take way longer.
By the way, referring back to the image of the cores on the Q-tip, notice that the few cores shown are stuck together with some sort of a transparent, black tinted, sort of shellac, this was the result of heating them to red hot. These cores are not stuck together because of partial melting, the shellac like substance that accumulated on the surfaces is definitely the culprit. Not sure what this is all about, it's as if something came out of the metal, such as how silicone comes out of bronze bushings that are impregnated with that stuff. For all I know, maybe these cores are palladium and this is how that metal reacts when heated, but just as with platinum, I've not ever messed with palladium either, so I'll wait to here from you guys, hopefully one of you will recognize what's going on here.
Anyway, let me know what you gentlemen think, thanks.
So let me know what you gentlemen think.
