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Sylvia Rose

Metal Salts: Ancient History to Modern DIY

Metal salts are compounds created from metals and acids. In history and today they enjoy uses in beauty, natural health, chemical medicine, agriculture and industry. Many are known in ancient civilizations and some can be created as modern DIY projects. Read on.



Illustration of Various Metal Salts
Various metal salts, artistic

Metal salts are a diverse group of chemical compounds made of metal cations and various anions. These salts have long been a significant part of human history. They include iron sulfate, copper chloride, calcium lactate, magnesium sulfate (Epsom), and potassium chloride.


A Brief History of Metal Salts


The story of metal salts is a long one. In ancient Egypt, copper sulfate is used in medicine and embalming. Alchemists of the Middle Ages seek to understand these substances through experimentation. The Renaissance is a prolific period as scientists explore chemical properties.


Metal salts have also influenced art significantly. For example, the discovery of ultramarine or cobalt blue, sourced from cobalt salts, brings an intense blue pigment to the artists' palette. This vibrant blue is now made synthetically and beloved in contemporary artwork.



pile of gold


Types of Metal Salts - 5 Examples


  1. Iron Sulfate


Iron sulfate (FeSO4), commonly known as ferrous sulfate, is essential in various fields, including agriculture and medicine. In fertilizer it improving soil quality, improving crops like corn and wheat. In health, it treats iron-deficiency anemia, a problem of 1 in 8 women (US).


In ancient times, ferrous sulfate used as a dye for textiles as well as a mordant. Historically, it is essential in the production of iron.


How to Make Iron Sulfate:


  1. Begin with iron filings or iron scraps.

  2. Carefully add diluted sulfuric acid to the iron, observing the reaction.

  3. Gently heat the mixture until fully dissolved.

  4. Let the solution evaporate to reveal iron sulfate crystals.


A mild sulfuric acid is created by steeping peeled sliced onions in water for several days. It's the ingredient responsible for onion tears, the bane of chefs.



onion cells microscope
Onion cells under a microscope

This is the ancient procedure for making sulfuric acid:

The maker burns sulfur together with saltpeter (potassium nitrate, KNO 3), in the presence of steam. As saltpeter decomposes, it oxidizes the sulfur to SO 3, which combines with water to produce sulfuric acid.

Sulfuric acid is highly corrosive and causes painful scarring chemical burns. Use all safety precautions. Ferrous sulfate itself is not considered toxic and its products are often recommended to treat iron deficiencies.




Ferrous Sulfate
Ferrous Sulfate aka Green Vitriol
  1. Copper Chloride


Copper chloride is known for its striking blue-green color and is vital in the electronics industry. It conducts electricity effectively, which is crucial for creating printed circuit boards. Roughly 45% of the copper produced worldwide goes into electrical applications.


How to Make Copper Chloride:


  1. Start with copper oxide or copper carbonate.

  2. Slowly add hydrochloric acid, watching for bubbling.

  3. After the reaction, filter to remove any leftover solid materials.

  4. Evaporate the liquid to yield blue copper chloride crystals.


Copper chloride (CuCl2) has been integral to the development of ancient civilizations. The vibrant blue-green color of copper salts makes them valuable for ornamentation.


In science, copper chloride has been used in chemical reactions, particularly in the synthesis of various organic compounds. It's also applied as a fungicide and algaecide in agriculture.


Hydrochloric acid has a known history dating to the 8th century, when it's used by alchemists. It's first prepared in a controlled way by Jabir ibn Hayyan. The medieval name is spirit of salt, referring to its derivation from salt (sodium chloride) and sulfuric acid.



  1. Calcium Lactate


Calcium lactate is an organic salt formed from lactic acid and calcium, an alkaline earth metal. Historically, it's used in the food industry as a preservative and a source of calcium, vital for human health. It can be found in dietary supplements to support bone health.


Calcium lactate provides dietary calcium, essential for strengthening bones and teeth. An estimated 40% of adults do not get enough calcium, making this compound significant in nutrition.


How to Make Calcium Lactate:


  1. Combine lactic acid with calcium carbonate.

  2. Stir until fully reacted, creating a mixture of calcium lactate.

  3. Filter the solution to isolate the solid calcium lactate.


Calcium carbonate is familiar in crushed eggshells, limestone, chalk, shellfish skeletons and pearls. Apart from calcium and protein, eggshells also have trace amounts of other minerals such as strontium, fluoride, magnesium, and selenium, which can contribute to bone health.


Lactic acid is primarily manufactured through bacterial fermentation, used in cheese. It can also be produced through chemical synthesis from acetaldehyde. Fermentation accounts for the majority of lactic acid production. Lactic acid can be acquired commercially.



egg shells broken

  1. Magnesium Sulfate (Epsom Salt)


Epsom salt, or magnesium sulfate (MgSO4), has a rich history of both medicinal and agricultural use. Magnesium sulfate is valued for its relaxing properties. Added to baths it can soothe sore muscles and relieve stress, giving skin a healthy glow.


How to Make Magnesium Sulfate:


  1. Add sulfuric acid to magnesium oxide.

  2. Stir thoroughly until dissolved.

  3. Evaporate the solution to yield magnesium sulfate crystals.


A common magnesium supplement, magnesium oxide is found at drug stores and health stores. So is Epsom salt.



enjoy a bath
A luxurious bath
  1. Potassium Chloride


Potassium chloride (KCl) is a type of metal halide salt made of potassium and chlorine. It has no smell and appears as white or colorless glassy crystals. When solid, it easily dissolves in water. Its solutions taste like salt. Potassium chloride can be found in dried lakebed sediments.


Potassium chloride is crucial as a potassium supplement in fertilizers and as a salt substitute for those on low-sodium diets. Approximately 98% of the body’s potassium is found within cells and is vital for heart health and proper body functions.


How to Make Potassium Chloride:


  1. Start with potassium carbonate or potassium hydroxide as your base.

  2. Add hydrochloric acid to the mix gradually.

  3. Filter to remove impurities and then evaporate the residue to obtain potassium chloride crystals.



potassium chloride
Potassium chloride powder

Facts About Metal Salts


  • Diverse Applications: Beyond industrial uses, metal salts find roles in medicine, agriculture, and even everyday cooking.

  • Colorful Chemistry: Many metal salts boast vibrant colors and are essential in dye and pigment production.

  • Eco-Friendly: Certain metal salts contribute to environmental efforts. Metal salts are being explored for their potential to remediate polluted environments. For example, iron sulfate can help treat contaminated groundwater.

  • Historical Significance: The quest for transforming base metals into gold involved significant study of metal salts and their interactions.

  • DIY Potential: Creating metal salts at home can be a fun, hands-on experience, promoting engagement with chemistry.

  • Role in Agriculture: Many metal salts serve as crucial fertilizer components. Potassium chloride, for instance, is a primary ingredient in many fertilizers due to its potassium content.

  • Industrial Applications: Metal salts like copper sulfate are indispensable in electroplating, a process that coats metals with a layer of copper to prevent corrosion and enhance appearance.

  • Medical Uses: Beyond dietary supplements, metal salts have therapeutic uses, such as magnesium sulfate for pre-eclampsia treatment in expectant mothers.



Brown glass medicine bottles
Brown glass medicine bottles

Non-Fiction Books:


Fiction Books:

READ: Lora Ley Adventures - Germanic Mythology Fiction Series

READ: Reiker For Hire - Victorian Detective Murder Mysteries




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