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THe ALUNDUM CRUCIBLE AS A SUBSTITUTE FOR THE 
GoocH CRUCIBLE. 
GEORGE L. CLARK. 
In order to test the efficiency of the recently introduced unglazed 
Alundum crucible, when used for the purposes in quantitative analytical 
chemistry generally assigned to the ordinary Gooch crucible, four different 
series of analyses were undertaken. These involved the determination of 
silver by precipitation as silver chloride, copper as cuprous sulpho-cyanate, 
aluminium as aluminium oxide from ignited aluminium hydroxide, and barium 
as barium sulphate. Such a selection was made in order to obtain as widely 
different precipitates as possible, as regards size of particles, ease of filtra- 
tion and media in which produced, and at the same time be in general usage. 
Both the Alundum and Gooch crucibles permit filtration, drying and 
weighing without disturbing the precipitate, but the porous nature of the 
former of course does away with the preparation of an asbestos mat. To 
discover whether or not such an advantage as well as others claimed for the 
Alundum crucible by its manufacturers, such as capability of withstanding 
very high temperatures, is sufficient to warrant its wide adoption for use in 
accurate quantitative analysis, was therefore the object in view in this study. 
One crucible only was used for the determinations in one series, in order 
to discover what would be the effect of continuous usage and how thoroughly 
it might be cleaned in preparation for the next analysis. In each case the 
empty crucible was heated thoroughly for one hour in the drying oven at the 
temperature at which the precipitate was later to be dried. The apparatus 
for the filtration was that used with the Gooch crucible, since any more com- 
plicated or expensive apparatus would per se be a distinct disadvantage. 
I. The determination of AgNO; as AgCl. 
In these analyses 50 c. c. portions of a solution, each containing .2432 
grams of pure AgNO; were used. In the first trials a solution of Kahlbaum’s 
chemically pure NaCl was used to precipitate the AgCl from the hot solution 
of AgNO; while rapidly stirred. Stirring was continued for two minutes, 
the precipitate allowed to settle, filtered through the crucible, washed with 
water and then dried at 140°. 
