The calorimeter is shown in the figures B and B′. It consists of a wooden box closed on one side by a glass plate G and on the other to the heighth F by a small board on which a calorimeter of ordinary construction is placed. The cylinder of the calorimeter is seventy millimeters high and forty-seven millimeters in diameter. [Illustration: FIGURE 13. REGNAULT’S APPARATUS FOR DETERMINING THE SPECIFIC HEAT OF SOILS. ] This part of the apparatus is supported by triangular pieces of cork. A delicate thermometer is fastened to the top of the box of the calorimeter and the value of the degrees is so arranged that about twelve of them correspond to about one degree C. The scale of the instrument can be arbitrarily fixed and the temperature of any part of it determined by comparison with a delicately graduated thermometer. Near the thermometer in the calorimeter is a stirrer made of a very thin copper disk with a bent rim. This stirrer is operated by means of a silk cord moved by appropriate machinery. The reading of the thermometer is made through a glass plate and this should be protected from the heat of the body of the observer by a paper screen. The test tube E is first filled with the substance, whose specific heat is to be determined, and weighed. It is then placed in the water bath until constant weight is reached. After constant weight has been obtained the apparatus is again dried and the exact weight of the moisture lost thus determined. The test tube is then placed in the apparatus A closed with a well-fitted cork, the top covered with cotton and heated in the aqueous vapor for about one hour. The heating apparatus should be far removed from the calorimeter so that the temperature of the latter cannot be influenced thereby. Meanwhile the calorimeter is filled with water which has stood in the room for a long time until it has acquired, as nearly as possible, the room temperature. The quantity of water is such that the water value of the whole of the calorimeter together with the immersed portions of the thermometer and stirrer shall amount to exactly 100 grams. A few minutes before bringing the substance into the calorimeter, the stirring apparatus is put in motion and the temperature observations are commenced. These should be at intervals of twenty seconds and should be continued until ten observations have been made. Meanwhile the height of the barometer is also read. A few seconds before the tenth interval the apparatus A is brought quickly to the calorimeter and its contents emptied into it at the moment of the tenth interval. The apparatus A should be removed as quickly as possible after its contents are emptied.