52 



MR J. Y. BUCHANAN ON THE 



Departure of the Mean Temperature from the Standard Temperature 

 during a Series of Observations. 



A. 



B. 



C. 



A. 



B. 



C. 



Number of Series of 



Observations made 



with Hydrometer No. 



During which the 

 Departure of the 

 Mean Tempera- 

 ture from the 

 Standard 

 Temperature was 



The Numbers 



under A expressed 



as Percentages. 



Number of Series of 



Observations made 



with Hydrometer No. 



During which the 

 Departure of the 

 Mean Tempera- 

 ture from the 

 Standard 

 Temperature was 



The Numbers 



under A expressed 



as Percentages. 



17 



21 



17 



21 



17 



21 



17 



21 



554 

 35 

 69 

 19 

 17 

 32 

 10 



3 

 19 



3 

 52 



5 



260 



39 



56 



26 



18 



12 



17 



3 



9 



2 



23 



2 



°G. 

 0-000 

 0005 

 0010 

 0015 

 0020 

 0-025 

 0-030 

 0-035 

 0-040 

 0-045 

 0-050 

 0-055 



66-3 

 4-2 

 8-2 

 2-3 

 2-0 

 3-8 

 1-2 

 0-4 

 2-3 

 0-4 

 6-2 

 0-6 



54-2 

 8-2 



11-7 

 5-5 

 3-8 

 2-5 

 3-5 

 0-6 

 1-9 

 0-4 

 4-8 

 0-4 



2 

 1 

 1 

 2 

 1 

 

 3 

 1 

 6 

 2 



3 

 3 

 1 





 4 

 

 

 

 1 

 



•c. 



0-060 

 0-065 

 0-070 

 0-075 

 0-080 

 0-085 

 0090 

 0-095 

 0-100 

 0-120 



0-2 

 0-1 

 0-1 

 0-2 

 Oi 

 0-0 

 0-4 

 01 

 0-7 

 0-2 



0-6 

 0-6 

 0-2 

 0-0 

 0-9 

 0-0 

 0-0 

 0-0 

 0-2 

 0-0 



Total, 837 



479 



100-0 



1000 



variation of temperature, and the same was the case in 55 "2 per cent, of the series 

 made with No. 21. If we consider the series made with both hydrometers for which 

 the variation of temperature was not greater than 0'05°, the percentages are almost 

 identical, namely, 89-5 for No. 17 and 89-2 for No. 21. 



The maximum departure of the mean temperature from the standard, during any 

 single series of observations, was 0'12° C. ; the mean departure was 0'0075° C. 



The maximum range of temperature while a series of nine observations was being 

 made was 0"30° C. ; the mean range of temperature for the 1316 series of nine observa- 

 tions each was 0"018° C. 



These statistics show that the efforts made to secure constancy of temperature 

 were successful. 



Seotion IV. — The Control of the Temperature of the Laboratory. 



§ 22. A laboratory is an inhabited room, and in Northern Europe the temperature of 

 such apartments lies generally between 12° and 20° C. Consequently we find that a 

 large amount of specific gravity work has been done at 15° C. by Gerlach, at 19-5° C. 

 by Kremers, and at 17 '5° C. by others ; while the calorimetric work by Julius Thomsen, 

 extending over the last half-century, was all done at the temperature 18° C. 



It is always possible to raise the temperature of a laboratory or a dwelling-room, 

 but it is not easy to lower it below the atmospheric temperature outside of the house. 

 The temperature of the atmosphere in our latitudes rises often above 20° C. in summer, 

 and then a temperature as low as 19'5°C. cannot be maintained. Similarly, in cold 



