Notices of the proceedings at the meetings of the members of the Royal Institution of Great Britain with abstracts of the discourses . nd the calorimeter itself shouldbe filled with some of the same fluid. This will maintain very closelythe constant temperature required. When any suckhur backseems to be taking place, the calorimeter should be emptied and filledanew from the larger flask A. The tube between the calorimeter andthe gas receiver should be of the size of wide quill tubing, and itslower end should be so arranged below the surface of the liquid inthe collecting vessel, as to give no
Notices of the proceedings at the meetings of the members of the Royal Institution of Great Britain with abstracts of the discourses . nd the calorimeter itself shouldbe filled with some of the same fluid. This will maintain very closelythe constant temperature required. When any suckhur backseems to be taking place, the calorimeter should be emptied and filledanew from the larger flask A. The tube between the calorimeter andthe gas receiver should be of the size of wide quill tubing, and itslower end should be so arranged below the surface of the liquid inthe collecting vessel, as to give no resultant pressure. With suchprecautions, results may easily be obtained correct to within2 per cent. The instrument having been set up and filled with liquid air,according to the above directions and precautions, an experiment isconducted by tilting up the little test-tube, previously cooled orheated, thereby dropping into the calorimeter a portion of any sub- 1904.] on Linnid Hydrogen Colorimetry. stance previously weighed. The substance, if left under normalconditions in this way falls from the temperature of the room to that. of liquid air. The heat given up by it to the liquid air volatilisessome of it, which is carried off by the branch tube and measured inVol. XVIT. (No. 1)8.) 2 R 588 Professor Sir James Dewar [March 25, the graduated receiver F. Immediately preceding or following tinsobservation, a similar experiment is made with a small portion of aselected standard substance, namely, lead. The quantity of lead is sochosen as to produce about the same volume of gas in the receiver asthat supplied by the portion of substance experimented on. By thismeans, the circumstances of the two observations are made as similaras possible, and thereby many sources of error arc eliminated. When the hydrogen calorimeter is to be used, the temperaturebeing so much lower than in the liquid-air cal jrimeter, we have tokeep the ordinary atmosphere from entering the mouth of the tubeG by
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