146 Scientific Proceedings, Royal Dublin Society. 
work done by Fresenius, Emmerling,” Weber and Sauer,° and 
Forster. Fresenius and HEmmerling experimented with boiling 
solutions, while Forster, as well as Weber and Sauer, investigated 
the action at ordinary temperatures also. 
Emmerling’s results are instructive in showing that a very 
considerable action is induced even by exceedingly weak solutions. 
Thus, on boiling about 400 c.c. of a solution of caustic potash 
in a flask of 600-700 c.c. capacity, he found that the latter expe- 
rienced a loss in weight per hour for different concentrations of 
the potash solution, as follows :— | 
Per Cent. Per Cent. Per Cent. 
Const a 4 al 8 3 ORK 0-025 0-005 
Loss of weight of vessel per hour, . 0°0115  0:0070 0-0027 
Forster proved that at ordinary temperatures a weaker alkaline 
solution may exercise an actually greater effect on glass than a 
stronger one, while the relative action of a weaker solution appears 
to be always greater than that of a stronger, as the following table 
of his results show :— | 
Grms. NaOH 
in 100 C.c. Loss in mgs per 100. sq. cms. of surface. 
solution. 
I II. III IV 
46 1°8 eg 2-0 87 
10 5°2 6°3 6°] 6°6 
1 39 4°5 5-1 5:5 
In the above experiments the Roman numerals refer to different 
kinds of glass, which were exposed to the solution at ordinary 
temperatures for fifty days in each case. 
The only experiments on the action of baryta water on glass of 
which we have been able to find an account are those of Weber 
and Sauer, who employed a saturated solution, which was kept in 
100 c.c. flasks of different varieties of glass for a period of two 
“¢ Quantitative Analysis,’’ 11., p. 798. 
“‘ Liebig’s Annalen,’’ 150 [1859], p. 257. 
‘Berichte d. deutsch. chem. Ges.,’’ 25 [1892], pp. 70 and 1814. 
Ibid., p. 2494. 
CO te aes 
