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Benjamin Ward Richardson 2026-10-31

Figure 1.
Portrait of Benjamin Ward Richardson
. Photograph by Henry Joseph Whitlock, late 1860s–1870s, National Portrait Gallery Ax18349; public-domain reproduction hosted by Wikimedia Commons. **Source**.

A physician who described Richardson's ether spray.

Past exam of the medicine course of the University of Oxford / 1866 / First examination / Physics / 9 / Solution 2026-10-31

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Evaporation cools the remaining material when the escaping vapour takes energy from it faster than the surroundings supply heat. For an observable demonstration, compare two similar thermometer bulbs at the same initial temperature, one dry and the other wetted with a volatile liquid. Expose both to the same controlled airflow. The wetted bulb falls in temperature; the effect depends on vapour removal and environmental conditions. Another demonstration is continued heating during boiling at constant pressure: vapour is produced while the boiling liquid's temperature remains nearly constant. The supplied energy has not vanished; it contributes to the latent heat and expansion associated with the phase transition.

One calorimetry method estimates the specific latent heat of vaporization by condensing a known mass

m_{s}

of dry saturated steam at

T_{s}

into a known mass

m_{w}

of cooler water. Let

C_{cal}

be the vessel's heat capacity, and

T_{i}, T_{f}

the initial and final water temperatures. Assuming complete condensation without escaped steam or thermal losses,

m_{s} {L_{v} + c_{w} (T_{s} - T_{f})} = (m_{w} c_{w} + C_{cal}) (T_{f} - T_{i}),

(1)

L_{v} = \frac{( m _{w} c _{w} + C _{cal} ) ( T _{f} - T _{i} )}{m _{s}} - c_{w} (T_{s} - T_{f}) .

(2)

The last term removes the sensible cooling of the condensed steam. Weighing the receiving vessel before and after gives

m_{s}

only if splashing, evaporation and liquid carried in with the steam are controlled. A steam trap and an insulated transfer path address two distinct errors: droplets falsely counted as condensing steam, and cooling before the calorimeter.

The historical local application was Richardson's ether spray. A bellows atomizer dispersed diethyl ether into fine droplets, promoting rapid vaporization and withdrawal of heat from the surface; the cooling could produce local loss of sensation. Benjamin Ward Richardson's 1866 account describes this evaporative method and its apparatus. Its historical physiological language is not adopted as a modern description of nerve signalling, and the account does not establish that the method is appropriate for every operation.^[ref]

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