on the Analysis of the Carbonates. «855 
cess, which occupies from fifteen to twenty minutes, drawing 
through the apparatus fifty cubic inches of dry air, the bottle is 
several times gently shaken from side to side, to promote the es- 
cape of the combined carbonic acid from the liquid. The instru- 
ment is now withdrawn from the appendages, and again placed 
on the scale to be weighed. In this second weighing, it will 
sometimes happen, that thg apparatus loses while on the scale, a 
small amount of weight, rarely however exceeding a few thou- 
 sandths of a grain, arising as we have clearly proved, from the 
gradual escape of more of the combined carbonic acid from the 
liquid. {In such cases we repeat the process of aspiration, after 
which the weight remains without sensible diminution during 
the weighing. ‘ 
In using the pipette form of apparatus, for the deliquescent car- 
bonates, the substance to be examined is placed ina thin glass 
tube, previously weighed. The tube is then drawn out nearly to 
a point by the use of a weighed fragment of a glass rod over an 
alcohol lamp. Sufficient heat being applied thoroughly to dry 
the carbonate, the fine end of the tube is closed, and the whole 
suffered to cool down to the surrounding temperature. ‘The point 
of the tube is then removed with a sharp file, to allow air to en- 
ter, after which it is closed by the application of a small stopper 
of wax cement of known weight. In this condition the tube, to- 
gether with the little piece removed from its point, and the frag- 
ment of rod, are placed in the scale and counterpoised. ‘The en- 
tire weight, thus obtained, diminished by the sum of the weights 
of the tube, rod and stopper, gives the weight of the dry carbo- 
nate in the tube. Ke 
- The pipette being charged with acid and adjusted so as not to 
produce drops, the tube is allowed to fall into the bottle with such 
force as to be broken, and the cork is instantly secured in its 
Place. To inject the acid into the bottle, we attach the large 
drying tube to the upper drying tube of the instrument, and then 
Operate either by suction with the mouth applied to a little mouth- 
piece at the other end of the apparatus, or by connecting it with 
the appendage for aspiration. In all the other steps the process 
is the same as where the bucket is employed. 
The weight of the carbonic acid employed, being then accu- 
tately determined, the process has reached the stage at which it 
has heretofore been regarded as terminated, but numerous obser- 
