10x – Arsenic (99.9% purity) chunk approximately ½” x ½”.
Tiny fragments of this brittle metal was used to conduct the following microchems.

10x – A fragment of the As metal was dissolved in 1 drop HNO3 & 1 drop H2O.
The As digestion was extremely slow and required heat from cigarette lighter flame.
This image is the dried nitric acid solution containing the dried white Arsenic salts
The vapors produced a slight odor somewhat resembling vinegar.
There was also a peculiar taste in the mouth.
No typical garlic odor that Arsenic is famous of when burned. Occasionally, during the subsequent tests when heat was applied to solutions I sorta suspected I smelled something resembling an insecticide.

40x – Dried As salt crystals that have formed around the perimeter of the nitric acid solution.

10x – A single crystal of K2Cr2O7 was inserted into the dissolved As + nitric acid solution.
The potassium dichromate crystal began dissolving and no precipitant formed.
When the K2Cr2O7 had dissolved gentle heat was applied to underside of glass slide, which produced the results shown in next image.

10x – The reddish area is typical of forced dried K2Cr2O7 in a nitric acid solution. However, the green area is not typical. I suspect that the chromium has inter-reacted in some manner with the Arsenic.

30x – A magnified view of the preceding image focusing upon the reddish and greenish areas.

Note: Sodium Chloride does cause a precipitant. The NaCl simply dissolves like the potassium dichromate. Nor does the NaCl produce any significant or specific crystallization that could help identify Arsenic in a nitric acid solution.

Note: Arsenic metal does not dissolve in concentrated HCl.

40x – Arsenic fragment slowly dissolving in Aqua Regia (1 part HNO3 & 3 parts HCl).
Aqua-Regia seems to be the fastest way to dissolve this metal. Yet, even this method is still slow and requires heat to aid digestion.
Interestingly—when the A-R laden As solution is converted to a chloride state there remains an oily film.
Note: Metal arsenic barely and slowly dissolves in 1 drop HNO3 and 2 drops HCl with heat, but A-R is the best way to dissolve the metal.

The next image shows spheroids around the perimeter of the oily (dried?) chloride solution.

70x – These reddish, orange and blackish spheres appear along the edge of the oily film that should be a dried solution.
I have no idea why these spheres form, other than they are a form of arsenic that, perhaps heat caused the oily film to form these spheres.
I’ve seen these spheres occur many times in solutions that have been subjected to similar circumstances, but no known arsenic was present, nor was the chloride solution oily looking. Therefore, until many different tests are conducted these spheres are not reliable for determining the presence of Arsenic.

10x – A single crystal of potassium Iodide (KI) was inserted in the oily solution after 1 drop of HCl was added to make it liquid.
This immediate yellowish precipitant formed and continued to expand in circumference.

40x – A magnified view of the preceding image after about 30 seconds.
The yellow color is becoming more orange and the Iodide crystal is forming the unusual blue tinted gelatinous formation on top of solution.

40 – Another magnified image of the KI reaction to the HCl & oily arsenic solution, showing how the previously yellow is becoming more orange.

40x – After several minutes the whole precipitant began to dissolve leaving this small amount of the original.
Even though the KI induced precipitant re-dissolved I would use this microchem as one way to help determine the presence of Arsenic in this type of acidic environment.

40x – Because the previous KI precipitant finally dissolved I was curious and placed a single crystal of K2Cr2O7 in same solution and when a little heat was added this crystal formation became evident.
This is not a good methodology to combine reagents because too many possibilities enter into the outcome. Nevertheless, I sometimes do this and save a picture of the results for future test comparisons.

12x – A single crystal of K2CR2O7 (far left yellow spot) was inserted into another A-R digestion of Arsenic that was also converted to a chloride state.
No specific odor.
No precipitation occurred.
Obviously, there is a huge difference between this end result and the previous potassium dichromate results. Consequently, this image shows what the results would be without the Iodine contamination.
I would not consider K2Cr2O7 to be a good reagent to use in determining the presence of Arsenic in either a HCL or HNO3 solution.
However, perhaps NaCl and K2Cr2O7 are decent reagents that expose the possibility or probability that arsenic is present in a nitric solution if another element is present?

The next 5 images attempt to show that sodium chloride & potassium dichromate can be beneficial when Arsenic and Lead are in same solution.

40x – This image is the result of 1 drop H2O & 1 drop HNO3 acid solution of dissolved Arsenic and Lead.
This image is showing supersaturated crystals forming on the perimeter of solution.
Essentially, what I see is the frosted appearance of the crystal formations, which is a little different than for lead nitrate.

40x – Some supersaturated floating crystals which are partially frosted in appearance, which signals the presence of two or more dissolved elements.
There are two basic crystalline forms.

40x – A single Crystal of K2Cr2O7 inserted into a Arsenic & Lead solution, which were digested in water and nitric acid produced these various orange crystal shapes.
Lead chromate tends to the yellow color with some orange blades in a water/nitric solution, whereas these are orange only crystals that do not have the form of only Lead chromate. Thus, the potassium dichromate insertion created a precipitant that indicates the presence of 2 or more elements. Therefore, because only 2 elements were digested this type of precipitant can be used for future cross-reference.

40x – Two NaCl crystals were inserted into another 1 drop nitric acid and 1 drop water solution containing the dissolved Arsenic and Lead.
The focus is upon the peculiar needle shaped radiating crystals, which do not have the normal feathers that Lead develops. Therefore, this image might well be useful in determining the presence of Arsenic when combined with Lead after other micro-chems and other reagents also show the differences.

40x – Same image as the preceding, but the focus is on the un-dissolved sodium chloride (NaCl) crystals and the whitish ring surrounding the table salt crystals.

Note: I try to keep all images of precipitations for future reference.

The next 5 images are of Arsenic and silver digested in a solution of 1 part nitric acid and 1 part water.

30x – These unusual crystals are forming at the perimeter of the dissolved Arsenic and silver in a solution of 1 part nitric acid & 1 part water that is approaching a super-saturated dry state.
Arsenic nor silver by themselves make this crystalline formation in a similar solution. Therefore the question arises if this is some kind of combination (salt) of these two elements as a nitrate?

40x – More of the similar crystals as shown in the preceding image that have formed along the perimeter of the super-saturated As + Ag nitric/water solution.

40x – A water wetted toothpick tip picked-up a few sodium chloride crystals (only meant to get one or two), which was inserted into a solution of 1 drop HNO3 and 1 drop water containing dissolved Arsenic and silver.
These NaCl crystals are obviously precipitating silver chloride, but this is not exactly what silver chloride looks like in a solution of only silver nitrate.
There are some hints of brownish-yellow colors, which, again is not typical of silver chloride. Plus, after about an hour this silver chloride, which is normally light sensitive did not produce the typical violet color change. Consequently, although Arsenic has not been determined this precipitant clearly demonstrates that at least one other element is present and interfering with normal formation of silver chloride.

30x – A single crystal of K2Cr2O7 was inserted into another solution containing 1 drop nitric acid & 1 drop water that has dissolved Arsenic and silver.
The Red precipitated crystals strongly suggest silver, but these red crystals are not exactly typical of silver chromate. Thus, it becomes suspiciously obvious that another element is present causing co-precipitation or interference. Therefore, because there is only arsenic and silver present this image could be helpful in determining the presence of Arsenic and silver in an unknown dissolved mineral sample.

20x – This tooth pick tip was dipped in the nitric/water solution containing the digested Arsenic and Silver.
When the toothpick was ignited by a cigarette lighter flame the Silver was reduced at the tip and the brownish mass between the metal and black burnt area is not reduced metal, but I suspect it is a combination of un-reduced As & Ag,. It appears that arsenic did not interfere with silver being reduced to metal. In fact it is likely that some arsenic is reduced with the silver.

No garlic odor when the toothpick was burned, which I find unusual, unless if other elements are present may camouflage. Nevertheless, I do not make a habit of willingly breathing the acidic fumes.

To determine if arsenic is present with what appears to be reduced silver the toothpick metal tip was removed onto a glass slide as carefully as my non-steady hands allowed while watching through the microscope lens as the next image illustrates.

50x – Image of a portion of the brownish fiber that was between the metal toothpick tip and the black burnt wood, which appears to be wood contaminated with metal(s).
No attempt was made to determine if silver and arsenic is present.

70x – This magnified image of the toothpick metal end clearly illustrates that the metal is not completely metal. There is a fibrous structure, which might be partially metal and strands of wood.

50x – The toothpick metal end was dissolved in 1 drop nitric acid and 1 drop of distilled water and gently heated till dry.
These crystalline formations are the result of the drying process.
Both dried formations are not typical of silver nitrate.

10x – To the preceding image of the dried solution another drop of HNO3 and a drop of H2O was added.
A single crystal of NaCl (common table salt without any trace Iodine) was inserted into the solution, which instantly produced this bluish-white precipitate that is typical of silver chloride.

10x – After several minutes and with a little applied heat it is becoming evident that at least 2 elements are present.

When gently heating the solution the rising vapors gave an odor resembling coffee.

10x – The solution of the preceding image is almost dry, which has produced a whitish crude along a portion of the perimeter.
There are two areas of definitely bluish white silver chloride, but it is clearly contaminated.
This quick microchem confirms that the reduced silver was contaminated with arsenic.

This next 2 images show a similar situation where Arsenic does not reduce.

20x – This toothpick tip was inserted into the original dissolved Arsenic in nitric acid and then ignited.
No metal was reduced.
There is a slight brownish tip suggesting some kind of element, which, in this situation is known to be arsenic.
The toothpick was reignited and results are shown in next image.

40x – A magnified view of the preceding image.
No metal is reduced.
The only evidence that metal is present is the white burnt area and that the down-dipping light brownish-yellow toothpick tip that gravity has reacted upon.

Many alternative reagents can be used to confirm or deny the presence of Arsenic in a solution. I have only used a few here to begin the process of being able to make an accurate determination of the presence of Arsenic. When time and circumstances allow more microchems will be conducted with various alternative reagents.