# Silver Contact Points



## Anonymous (Apr 11, 2008)

Processed approximately 2 lbs of contacts, from various sources, here are the results.

The silver is in solution waiting filtration/ precipitation, using copper  

The heavy contacts from Manitoba Hydro have turned black in color, using side cutters found these to be hard and brittle still metallic inside with some weight left to them, non magnetic.

Then some other large contacts did not dissolve, using side cutters found these to be soft almost what you would expect from pure silver. The outside color is matted with the inside a bright silver color, these have weight to them and are non magnetic.

Then there are some foils, bright and shinny, positive for magnetic.

Then we have some gold buttons with some fines floating. 

Here is what I have done, processed the 2lb lot using 50/50 nitric with water. Then when I discovered the undissolved contacts decanted the solution adding 70% nitric to the remaining contacts overnight.

Now I would like to know what metal to expect from these contacts which did not dissolve.


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## Anonymous (Apr 11, 2008)

Contacts can be one of a great many alloys some contain gold, platinum, palladium, most contain silver, tungsten, cadnium oxide.


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## Lou (Apr 11, 2008)

Easy way to differentiate platinum from tungsten is heat--Pt and many of its alloys will not oxidize. Tungsten will at high temperatures (above red heat).

Pd, can be distinguished by adding a drop of HNO3 to it...should turn brown.


Lou


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## Anonymous (Apr 12, 2008)

james122964 said:


> Contacts can be one of a great many alloys some contain gold, platinum, palladium, most contain silver, tungsten, cadnium oxide.


This is true, and this is why this newbe is trying to distinguish what has been left behind from my process untouched by the HNO3.

I have thus far been taught silver bearing contacts which have been alloyed with tungsten retain their original shape after being processed in HNO3. These will break apart easily, if any silver remains inside you will see a thin line, meaning you have not left them long enough in your acid or the acid ran out before completion.

This is the reason I decanted my pregnant solution adding fresh HNO3 at 70% strength, which was based on a comment by Lou in another post of mine regarding this lot of contacts I have only now processed.

There is about 100 grams of these smaller contacts left untouched by my concentrated heated HNO3 , so yea I'm very excited about it all.

Thanks Lou I will give your suggestions a go in the morning, hopefully there is some Palladium in there for the wife.

A side note: My Hokes book was mailed out yesterday. In the meantime will stannous chloride test palladium from my acid. I do have a brown mud that settled on the bottom of my filter.

Best Regards to all

Gill Elmgren


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## Harold_V (Apr 12, 2008)

gustavus said:


> Processed approximately 2 lbs of contacts, from various sources, here are the results.
> 
> The silver is in solution waiting filtration/ precipitation, using copper
> 
> The heavy contacts from Manitoba Hydro have turned black in color, using side cutters found these to be hard and brittle still metallic inside with some weight left to them, non magnetic.



I would expect that the remnants are tungsten. Do they have a waffle pattern on the side that was affixed to the buss bar? Is there a distinct line in the center? That is a sign of a tungsten/silver contact that has not been completely leached of silver. It may require a prolonged boil in nitric/water, but all the silver can be recovered. 



> Then some other large contacts did not dissolve, using side cutters found these to be soft almost what you would expect from pure silver. The outside color is matted with the inside a bright silver color, these have weight to them and are non magnetic.



No clue what they might be, but palladium is soluble in nitric, so it isn't palladium. The resulting solution from dissolving palladium is a dark brown color. When mixed with silver and copper, you'd expect a dark green/brown solution. You should not have any brown solid substances from palladium. I would suspect traces of iron. 

Harold


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