COMPRESSIBILITY OF GLASS. 591 
TABLE I.—Comparison of Manometer No. 2 at 12°5° C. with Piezometer K, No. 4, 
in Ice melting under Pressure. 
Apparent 
Number | Pressure in | Contraction of 
Piezometer K, No. 4, contains at atmospheric pressure of Obser-| Divisions of} Water per 
774 cub. cents. of water. vations |Manometer| thousand in 
meaned.| No. 2. Piezometer 
K, No. 4. 
A H 
4 26:08 4:0228 
Temperature of manometer, 12°55° C. a 30°28 46534 
: s ae , iL 36°20 55972 
Piezometer immersed in ice melting under pres- ; ; 
2 5 40:08 61045 
sure represented by A. Probable tempera- 3 50-08 7-6043 
ture varying from —1° to 0° C. . 3 60-20 9:1057 
3 70°08 105163 
Total number of observations ~. , d el ede 
Mean reading of manometer . : : : 43°61 
Mean apparent contraction of water in piezo- 
meter ; F : : : ‘ : 66495 
Dividing the mean apparent contraction of the water in the piezometer by the 
apparent compressibility of water in glass 0:04868, we have for the pressure 
corresponding to a rise of 43°61 divisions on manometer No. 2 at 12°5° C. 
aa Beets 
= 004868 = 0-04868 ’ 
= 156°6 atmospheres. 
But this pressure produces a rise of 43°61 divisions on manometer No. 2. We 
have thus for the value of one division on the manometer 
_ 136-6 
a AST 
3°132. 
II 
Hence, to convert readings of manometer No. 2 into atmospheres, we have to 
multiply by 3132, the difference of the manometer reading under pressure and 
that at atmospheric pressure. 
In another series of experiments piezometer K, No. 4, was compared with 
