‘Lerts & Braxe—The Carbonic Anhydride of the Atmosphere. 147 
‘months. The loss in weight in mgs. which each experienced was 
found to be as follows :— 
Glasshe ms) ce Mt Otoiete Ope Oro tO. Oe ROL LT 
IDG ohh iee IE TOE. BEG ME ab) 9 We ot ve 
It seemed to us to be of some importance to ascertain, if possi- 
ble, the exact nature of the action of baryta water on glass. Isa 
soluble silicate of barium formed or an insoluble one, which in 
-our experiments was eventually dissolved by the dilute acid? 
Does the glass dissolve as such, or are certain of its constituents 
alone removed ? 
Before, however, describing our experiments on these points we 
may mention that other chemists have drawn attention to the 
action of baryta water on glass as a possible source of error. Thus, 
Reiset! says, “en effet les vases en verre dans lesquels on con- 
serve de l’eau de baryte perdent généralement leur transpa- 
rence. Le verre parait attaqué et comme décomposé: les boules 
-des barboteurs, en verre soufflé, présentent souvent de nombreuses 
stries blanchatres qui ne disparassent pas aprés un lavage avec 
Vacide nitrique faible.” He, however, did not find that the titer 
-of the solution was disturbed. 
Blochmann,? quoting Ebermayer’s results, says that the latter 
observer abandoned the “ flask ”’ method in favour of the “ aspira- 
tion” method, in consequence of the high results he obtained with 
the former (see Appendix, p. 225). Ebermayer attributed the 
-error of the flask method chiefly to the removal of baryta from 
the solution, and its fixation by the silica of the glass. 
The following experiments were made by us in order to ascer- 
tain the precise nature of the action of baryta water on glass :— 
(1). Four Winchester quart bottles of greenish glass were each 
charged with 50 c.c. of the baryta solution (1 c.c.=0'1 ¢.c. CO: at 
N. 1. P.), then closed with stoppers, well shaken, and placed on 
their sides for eight days, during which time they were occasionally 
shaken. ‘Their contents were then filtered into a platinum dish, 
the bottles rinsed out two or three times with distilled water, and 
the rinsings poured through the same filter. 1 ¢.c. of strong 
hydrochloric acid was then added, and the dish heated on a water- 
MUI Elec cs Se al 
1 « Annales de Chimie et de Phys.”’ [5], 26 [1882], p. 175. 
2 ILO2, Cilay Wo B80 
