Why were Henry Cavendish’s measurements of gases considered unusually accurate?

Henry Cavendish’s measurements of gases were considered unusually accurate because he employed rigorous quantitative experimental methods that prioritized reproducibility and precision.1

His approach was distinguished by several key practices:

• Standardization and Refinement: He worked closely with instrument makers to improve existing tools rather than relying on standard equipment. Notably, he utilized a high-precision balance made by the craftsman Harrison, which was among the finest of the 18th century.1
• Methodological Rigor: Cavendish consistently identified and accounted for potential sources of error in his experiments.1
• Statistical Analysis: He ensured the reliability of his findings by taking the mean of the results from several experiments.1
• Innovative Techniques: In his work on eudiometry, he developed a new eudiometer that allowed him to achieve superior results using methods that others had previously found inexact.1

These meticulous habits allowed him to perform experiments of such high quality that he even detected a small residue of gas—later identified as argon—that others had overlooked or dismissed as error.1