=109. Method of Calculating Results.=—Let t represent the mean temperature of the beginning period of the experiment, and v equal the loss in heat per interval. Let t′ and v′ represent the same values for the end period. Let θ₁, θ₂, θ₃, etc., represent the temperature at the end of the first, second and third intervals of the middle period and θ₀ the temperature at the beginning of the middle period and θₙ the end temperature of of the middle period. Let τ₁, τ₂, τ₃, ... τₙ, represent the mean temperature of the single intervals; then τ₁ = (Θ₀ + Θ₁)/(2); τ₂ = (Θ₁ + Θ₂)/(2), and τₙ = (Θ_{n–1} + Θₙ)/(2). The constant C represents the correction which must be applied in order to determine the true increase of temperature in the calorimetric system. The expression θₙ − θ₀ + C represents the true temperature increase of the calorimetric system which we may represent by Δθ and θₙ + C represents the true maximum, that is, the end temperature, which by exclusion of external influences is reached. The correction C, as already indicated, is to be added to θₙ − θ₀ when it is positive and is to be subtracted therefrom when it is negative. The numerical value of C is usually very small, and, in the experiments indicated, varied between zero and one division of the thermometer employed, that is it seldom exceeded one degree. =110. Illustration.=—The method of determining value of specific heat is best illustrated by an example: In one determination the water value of the calorimetric system, including stirrer and thermometer was 2.50 grams, the weight of water added was 97.50 grams and the total water value of the system 100 grams. The substance was dried at 100° and weighed in five envelopes: Total weight 31.423 grams. The envelopes alone weighed 10.654 „ Weight of the soil taken 20.769 „ The envelopes holding the soil were made of brass with zinc ends, the specific heat of which is 0.0939 and the water value of the whole of the envelopes was 1.0004 grams. Since, however, the ends were soldered on with zinc the true water value was somewhat smaller being equal to 0.8692 gram. The data of the observations were as follows: Corrected height of barometer 699.6 millimeters. Intervals between the observations 20 seconds. No. of Temperature on the Observations. arbitrary scale of the thermometer. First Period { 0 162°.6 „ {10 162°.9 = θ₀ (Moment of immersion.)