Reference points on the Réaumur temperature scale: What are the ice point and steam point (fixed points) on the Réaumur scale?

Introduction / Context:
Several historical temperature scales predate or coexist with Celsius and Fahrenheit. The Réaumur scale, though largely obsolete, still appears in older literature and instrumentation. Recognizing its fixed reference points aids in conversions and interpretation of legacy data.

Given Data / Assumptions:

• Réaumur scale divides the interval between freezing and boiling of water into 80 equal parts.
• Standard atmospheric pressure is assumed.
• “Ice point” denotes equilibrium of ice–water; “steam point” denotes equilibrium of water–steam.

Concept / Approach:
On the Réaumur scale, ice point is 0°Ré and steam point is 80°Ré, by definition. This contrasts with Celsius (0° and 100°) and Fahrenheit (32° and 212°). Conversions follow linear relationships using these anchor points.

Step-by-Step Solution:

Verification / Alternative check:
Historical thermometry references and conversion formulas confirm these fixed points.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing Réaumur with Celsius or Fahrenheit in old engineering tables; always verify the units symbol (°Ré).

Final Answer:
0° and 80°