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Apothecaries' system

math Maturity 11-13 Next article →

Doctors and pharmacists once used a special way to measure medicine. This was called the apothecaries' system. It helped them be very exact with every dose.

Chambers 1907 p 1172 prescription example
Chambers 1907 p 1172 prescription example

This system was used for both weight and volume. Volume is a way to measure how much space a liquid takes up. Scientists also used these units for a long time. It was a very important tool for medical work.

Apothecaries weights 1800
Apothecaries weights 1800

Measuring medicine requires many small steps. The system broke a large pound into smaller parts. One pound was divided into twelve ounces. Each ounce was split into eight drachms. A drachm was then divided into three scruples. Each scruple was made of twenty grains.

Apothecaries weights 1800
Apothecaries weights 1800

This made it easy to measure tiny amounts. It worked just like the troy system used for gold. This kept the measurements very precise for health.

This way of measuring has a very old history. The units came from the ancient Roman weight system. Famous Greek doctors like Galen and Dioscorides helped pass these ideas down. They lived in the 1st and 2nd centuries. Their writings were very influential for many years.

DBP 1991 1490-R
DBP 1991 1490-R

Because of them, the system spread across Europe. It was used by many people for a long time. It stayed useful even as empires changed.

Different rules existed in different places. In the 19th century, many European cities had two systems. One was for general trade and one was for precious metals. In 1850, Ireland tried a new plan. They wanted to use the avoirdupois pound instead of the troy pound. This was meant to make buying and selling easier.

Apothecaries weights 1800
Apothecaries weights 1800

However, the United Kingdom passed a law in 1858. This law helped change how things were measured. It was a big step toward new standards.

Today, most people do not use these old units. The United Kingdom and the United States both changed. They moved to the metric system in 1971. This made measurements the same in many countries.

DBP 1991 1490-R
DBP 1991 1490-R

You might still see these units in old books. They are part of the history of how we care for people. Knowing about them helps us understand how science grew. It shows how we learned to be more exact.

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File:DBP 1991 1490-R.JPG
DBP 1991 1490-R.JPG
File:Chambers 1907 p 1172 prescription example.png
Chambers 1907 p 1172 prescription example.png
File:Apothecaries weights 1800.png
Apothecaries weights 1800.png
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