REVIEWS 319 
made by the authors of carbonic anhydride in the air of a weaving shed 
in a linen factory at Belfast, in which the use of the Pettenkofer method 
failed to give concordant results in duplicate determinations, led to 
the investigation of this method by the authors. The method finally 
employed is described in considerable detail, including the prepara- 
tion of reagents, and the apparatus used are figured. A large number 
of tests were made on artificial mixtures and subsequently on samples 
of air collected in the rooms and the grounds of Queen’s College, Bel- 
fast. The results are recorded in tabular form. 
Section III closes Part I of the memoir, in which ‘“‘ The Authors’ 
Experiments on the Action of Baryta Water on Glass and on Silica, 
and the Disturbing Effect of Soluble Silicates on the Delicacy of the 
Phenol-Phthalein Colour Reaction,” are discussed. 
The results obtained are of special interest. ‘The experiments with 
glass were made on the greenish-white glass of Winchester quarts bot- 
tles, using a dilute solution of baryta water of known strength. 1° of 
the baryta water is equivalent to 0.1% of CO, at N. T. P. The quanti- 
tative results for different time exposures are: 
After 48 hours - - - - - 0.002! gram of glass, 
oe WB 6é 2 = ye =; 0.0025 6 ce 
“ YD 66 i ey ia =) a fe) 0050 66 66 
“6 98 (6 ns 3 a a 0.0062 66 a) 
“ 98 “6 a < pa zs iS 0.0098 66 “6 
The action of alkalies on glass has been investigated previously by 
a number of workers, and the results here obtained by the authors are 
in accord with those of previous investigators in showing the very 
appreciable effect in a short time with very dilute solutions of the 
alkali, which increases with the time exposure. 
It is of interest here to compare Emmerling’s results obtained with 
boiling weak solutions of caustic potash (400%) in a flask of 600 to 
700° capacity, whose loss in weight per hour was found to be: 
0.25 percent KOH - - - o.o1t5 gram of glass per hour. 
0.025 6c iss “ce = a = 0.0070 oe ce “e 
0.005 66 “ 66 2 a os 0.0027 oe 6 66 
{n order to ascertain the exact nature of the action of the baryta 
water on the glass, a given amount of the Ba (OH), solution of varia- 
ble but known strength was introduced into the stoppered bottles and 
allowed to remain for a given number of days, when the solution 
