(80) 
TPR Bie oe. 
Temperature. Time in hours, Rise of the level in the Rise per hour. 
capillary in mm. in mm. 
— 5°0 23 104 4,5 
0° 20 48 2,4 
“emia a) 17 2 0,1 
10°,0 15 | 0,9 0,0 
15°,0 11 0,0 0,0 
17°,0 23 0,0 0,0 
20°,0 244 — 20 — 0,1 
From these observations follows that the transition point lies 
between + 10° and -+ 20°. More exact results would be obtained 
by prolonged observations at constant temperature. 
b. Electric determination. 
A transition element was set up as follows: 
white tin — 10°/, ammonium stannic chloride solution — grey tin, 
and its E.M.F. at different temperatures determined by PoGaEn- 
DORFF’s method. A Weston-cell was used as standard and a small 
accumulator as the working cell. 
Our transition cell stood in a thermostat. The change of pole 
occurred at 20°, 
7. The two methods thus lead to the result that the change 
grey tin = white tin 
has a transition point (at 1 atmosphere) at 20° C. 
Since all tin articles in every day use, consist of the white mo- 
dification, the above research leads to the striking result, that our 
whole tin-world exists, except on a few hot days, in the metastabile 
condition. 
Amsterdam, Chem. Laboratory of the University, 
June 1899, 
"=. are, 
