on the Analysis of ‘the Carbonates, : 347 
The instruments And processes which we are about to describe, 
are the suggestions of a long course of experience in the labora- @ 
tory—have been submitted to numerous and varied trials, and _ 
have been carefully compared with the modes in general use ; so 
that we feel some confidence in offering them, through the pages 
of this Journal, to the criticism of practical chemists. . 
I. Apparatus and process for the approximate analysis of the 
carbonates, 
The apparatus first to be noticed is a modification of that de- 
scribed by one of us (W. B. R.) in the Journal many years ago.* 
Even in its early and ruder form, this instrument was found to 
furnish useful approximate results, with so much more ease and 
expedition than the methods commonly employed, that of Rose 
included, as to prove of great value in the numerous economical 
analyses of calcareous marls and other materials in which we 
were then engaging. In its improved shape, combining greatly 
superior accuracy with increased facility of manipulation, we 
have used it very satisfactorily for the last eight years, in many 
hundred of the ordinary analyses connected with the geological 
surveys of Virginia, Pennsylvania and New Jersey. 
The instrument, as thus modified, is represented in fig. 1. It 
consists of a light flask or bottle, measuring about two cubic in- 
ches, a globular pipette drawn out to a very slender tapering tube 
| below, a gum-elastic bag secured air-tight to the top of the pi- 
pette, and a drying tube, filled for the middle two thirds of its 
length with chloride of calcium, and near the ends with loosely 
| packed cotton. The pipette and drying tube are passed through 
| a smoothly drilled cork, so as to fit air-tight, the former project- 
ing three fourths of an inch into the flask. The cork is so ad- 
-Justed as to be withdrawn along with the pipette, and the pipette 
-ischarged without separating it from the cork. This gives room 
for the introduction of the carbonate into the flask, and obviates 
the danger, after thé pipette has been charged with acid, of touch- 
ing its moistened beak to the cork. Lastly, the surfaces of the 
contains water, it is driven off at the same time with the carbonic acid, and of 
Course its quantity must be estimated in the usual way.—B. 8. Jr. 
“Vide Am. Jour. Vol. xxvu, p. 299. j 
