Apothecary Weights and Measures: Historical Symbols and Conversions
The apothecary system was the traditional method of measuring and dispensing pharmaceuticals in medieval and early modern Europe. Apothecaries used a unique set of weight units—including grains, scruples, drams, ounces, and pounds—to prepare remedies with precision. These units often appear in historical texts, cookbooks, and herbals. This guide explores these measurements, their Latin roots, and modern equivalents for practical application.
Apothecary Weight Symbols
| Unit | Symbol | Modern Equivalent |
|---|---|---|
| Grain | Gra. | 0.065 g or 64.7 mg |
| Scruple | ℈ | 1.2 g or 20 grains |
| Dram | ʒ | 1.772 g or 3 scruples |
| Ounce | ℥ | 31.103 g or 480 grains |
| Pound | lib. | 373.242 g or 12 ounces |
| Quarter | qr. | 93.3 g or 3 ounces |
| Half Quarter | s. | 46.65 g or 1.5 ounces |
| Handful (Manipulus) | m. | ~4 g (approximate) |
| Aureus | aur. | ~8 g (1.5 drams or 1/40 of a Roman pound) |
| Ana (equal parts) | An̄ | Used in prescriptions |
Conversion Notes
- 1 Pound (lib.) = 12 ounces (℥)
- 1 Ounce (℥) = 8 drams (ʒ)
- 1 Dram (ʒ) = 3 scruples (℈)
- 1 Scruple (℈) = 20 grains (Gra.) or 2 oboli
- 1 Obolus = ~10 grains or 0.65 g
- 1 Siliqua = ~4 grains (seed of the carob tree)
Example Conversion
A medieval receipt calls for "2 ℈ saffron." That equals:
2 × 1.2 g = 2.4 grams
According to the Encyclopedia Britannica, apothecaries' weight is a "traditional system of weight in the British Isles used for measuring and dispensing pharmaceutical items, based on the grain, scruple, dram, ounce, and pound."
Etymology & Roman Influence
Siliqua is Latin for the carob seed (also known as St. John’s Bread). In the Roman weight system, 1 scruple equaled 6 siliques. A typical comparison was: 1 grain of siliqua = 6 grains of lentil. Multiply that value six times and you reach a scruple. Wheat grains were another reference: 20 wheat grains = 1 scruple.
Herbs Commonly Dispensed by Unit
- Grains: Opium poppy, belladonna, and digitalis—potent and toxic herbs requiring exact micro-dosing.
- Scruples: Rue, hyssop, and saffron—used in antidotes, tonics, or coloring agents.
- Drams: Wormwood, valerian root, fennel—often brewed as digestive bitters or nervines.
- Ounces: Chamomile, horehound, and licorice root—used for infusions, decoctions, and syrups.
- Handfuls: Lavender, rosemary, sage—measured more freely for baths, poultices, or steams.
Apothecary Quick Reference
- Primary weight unit: Grain (barley or wheat)
- Primary volume unit: Minim
- Grain to gram formula: grain × 0.06479891
Frequently Confused Units
- Dram (ʒ) in apothecary = weight. In fluid measure, it's volume.
- Ounce (℥) differs from the avoirdupois ounce used in kitchens.
- Scruple (℈) may be confused with its Latin root "scrupulus" meaning a small sharp stone or hesitation.
Historical Herbs and Their Measurements
In early medical and culinary texts, herbs were often measured by volume (such as a handful or spoonful) or by apothecary weight. These units depended on the herb's form—fresh, dried, powdered, or infused. Here are a few historical examples:
- Rosemary: Commonly listed as a manipulus (handful), particularly in steams and baths.
- Rue: Often measured in scruples (℈), due to its potency—used in antidotes and purges.
- Chamomile: Frequently prescribed by the ounce (℥) for brewing decoctions.
- Wormwood: Typically used in grains or drams, depending on its role in bitters or vermifuges.
- Saffron: Measured by the scruple or dram because of its high value and strong effect.
Understanding these historical measures is essential for accurate interpretation of period recipes and remedies—especially for adult learners looking to apply them in reenactment, historical herbalism, or culinary history.
Influence on Modern Practice
The apothecary system laid the foundation for modern pharmacy by introducing standardization in drug measurement and dosing. Units like the grain are still used in medical prescriptions (e.g., aspirin dosage). Pharmacists today rely on metric systems, but vestiges of apothecary language persist in older texts, legal documents, and even dosage forms.
Contemporary Use in Herbalism
While modern herbalists primarily use metric and imperial units, some traditionalist or folk practitioners still employ apothecary measures. Recipes handed down through oral tradition or found in historical herbals often use drams, ounces, or scruples. Modern herbal schools may teach these units to help students interpret older texts and apply historically accurate methods.
📏 Explore More Historical Conversions
- Medieval Measurements and Conversions
- Ounce to Tablespoon Conversion FAQ (Dry)
- Spice Conversions: Ounces to Tablespoons
- Feast Budgeting & Cost per Person Guide
Learn how period cooks measured, converted, and planned for large feasts—using both modern tools and historical math.
Sources and References
- Wikipedia: Apothecaries' System
- RF Cafe: Apothecary & Avoirdupois Conversions
- Culinary Lore: Carat and Carob Seeds
- Wiktionary: Siliqua
- Prepositas His Practise (1600s Medical Manual)
- Zupko, Ronald E. “Medieval Apothecary Weights and Measures.” Pharmacy in History, vol. 32, no. 2, 1990, pp. 57–62. JSTOR
