540 



MR J. Y. BUCHANAN ON 



The stations at higher levels are all in Switzerland, and they are as follows in order 

 of elevation : — 



Place. 



Height 

 above the Sea. 



Place. 



Height 

 above the Sea. 



Metres. 



Feet. 



Metres. 



Feet. 



Zurich, .... 

 Fiesch, .... 

 Andermatt, 

 Pontresina, 



410 

 1054 

 1444 

 1820 



1345 

 3458 

 4738 

 5970 



St Moritz, 

 Eggischoni, 

 Julier Hospiz, . 

 Schafberg (Engadine), 



1860 

 2193 

 2244 

 2733 



6102 

 7195 

 7362 

 8966 



Of these places Pontresina, with St Moritz, was the most important. The most com- 

 plete series of observations on mixtures, as well as on single salts, was made there. A 

 corresponding series of observations on single salts was made on the Schafberg, which 

 rises immediately behind Pontresina, and about 900 metres above it. Shelter is 

 obtained at the top in the chalet which does duty as a restaurant, and it is approached 

 by a well made path. Experiments on mixtures of salts could not be made at this 

 station, because the weather became so persistently bad that the chalet was closed for 

 the season early in September. 



Of the other places on the list, St Moritz is taken as one with Pontresina, because 

 the difference of level is less than that corresponding to ordinary fluctuations of the 

 barometer, 



Zurich and Julier Hospiz were visited for the purpose of verifying the thermo- 

 meters by observing the temperatures of saturated steam, and the barometric pressure 

 by standard barometers at the same time and place. One or two observations with salts 

 were made at the same time, but they have only the value of isolated observations. 

 The boiling mixture of chloride of sodium was observed at all the stations, and it was 

 the only salt experimented with at Eggischorn, Fiesch, and Andermatt, as at that date 

 I intended to confine my observations to chloride of sodium alone. 



Tlie salts used in this research are the chlorides of sodium, potassium, ammonium, 

 barium ; the chlorate of potassium ; the nitrates of sodium, barium, strontium, and lead, 

 and the sulphates of potassium and ammonium. These salts were used singly, and also 

 in mixtures of not more than two salts each. The charge of the apparatus was usually 

 one-fifth of a gramme- molecule, but with sparingly soluble salts, such as nitrate of 

 barium or sulphate of potassium, one-tenth and sometimes one-twentieth of a molecule 

 were used. A watch, giving minutes and seconds accurately, was observed during all 

 the experiments. In the case of simple salts the time was noted when the steam 

 reached the salt, when the salt formed a magma, with the steam condensed, when the 

 maximum temperature was reached, when it began to fall, and when the passage oi 



