132 
INTRODUCTION TO PRACTICAL CHEMISTRY- 
ordinary glass lamp chimneys, figs. 24 and 25, by tying a 
piece of muslin, previously moistened, over their smaller 
ends, and inserting them in wide-mouthed bottles, as a, fig. 
24, or through pieces of tin or card, as b, fig. 25, in which 
case they can be placed on any wide-mouthed vessel. One 
great advantage of these glass displacers is, that the opera- 
tor can assure himself of the proper stratification of the 
powder, or moist mass. 
" When several operations are proceeding at the same 
time, and the attention of the operator is much occupied, it 
frequently happens that the process stops for want of a 
further addition of menstruum. In this case, the arrange- 
ment for continuous displacement, fig. 26, may be advan- 
tageously resorted to. A small-mouthed bottle filled with 
the menstruum will answer instead of the flask. The 
action is obvious ; as the liquid in the displacer descends 
below the mouth of the inverted flask, the fluid in the latter 
passes out, and preserves the level of that in the displacer." 
ART. XXVIII.— AN INTRODUCTION TO PRACTICAL CHEMIS- 
TRY, including Analysis. By John E. Bowman, Demonstrator of 
Chemistry in King's College, London. Philada. Lea & Blanchard, 
1849. pp. 303. 
The American student of Chemistry has certainly great 
cause of satisfaction in the publication of the numerous trea- 
tises on hisfavourite science which, within a few years past, 
have issued from the press, until each department, general, 
technological and analytical, has in turn been illustrated. 
The little work, of which the title page is placed at the head 
of this notice, will be found to possess some valuable charac- 
teristics serviceable to the apothecary who aims at qualify- 
ing himself for performing those occasional analytic re- 
