edited by DAVIDL. BYRUM
Inventory Control A "New" Filter Crucible Holder Joe B. Davis Department of Chemistry and Physics Winthrop College Rock Hill. SC 29733
During a quantitative analysis experiment involving suction filtration, a student used a polyethylene thistle top instead of the prescribed Walter filter crucible holder. She called my attention to some air leakage. After a moment of twisting and turning the thistle top, it worked beautifully. In fact, standard filter crucible holders (Walter and others) have been replaced
Globe High School 501 Ash Globe. A 2 85301
legation of "someone else" misplacing or stealing hislher gooch, especially when a clean crucible is being dried to a constant weight. The unit is ideal for sample runs in triplicate. The system can be assembled easily as outlined below. Cookie jars employed were 115-mm square, 130-mm high, 92-mm (ID) round-mouthed, fitted with an airtight plasticlined lid (Fig. 1). Jars used in o w laboratory are manufactured by Anchor Hocking Corporation, Lancaster, OH 43130 and are available in local discount stores for less than $2.00 each.
size thistle tops (Nalgene 6210 (listed only as a complete unit in 1983-84 Nalge catalog), Mallinckrodt P 430-0000) mate nicely with 2 5 6 or 500-&L filter flasks and 20- or 30-mL porcelain crucibles. Inside top diameter is the same as the Walter filter crucible holder. Leakage problems have been minimized by selecting flasks with more uniformly round necks. Thistle tops are lower in cost than other filter crucible holders, are not subiect to deterioration and contamination of crucibles with rubber particles, are unbreakable in normal use, and are likely to be in normal laboratory inventory.
Vibration Damper for Balances, Etc. Joe B. Davis
* Figure 1. Anchor Hackin@cwkie jar-115-mm square, 130-mm high, 92-mm (ID) round-mouthed, fined with an airtight plastic-lined lid.
DeDartment at Chemistrv and Physics ~ i n t h r o pCollege Rock Hill. SC 29733
All too often, balances and other sensitive equipment must
problem. Placement of a stack of a dozen bricks on each side of the balance (about 12-15 cm away) solved the problem without interfering with use of the balance. Use of a damping mass in this manner is quick and inexpensive enough to be worth trying.
Cookie Jar Desiccator B. Das Sarma West Virginia State College Institute. WV 251 12
We have used a cookie jar to devise a novel desiccator for the freshman laboratory. The system costs little to the chemistry department beyond the initial modest investment in dessicant and aluminum support platform. Instead of sharing a larger desiccator purchased and maintained a t a much higher cost, students can lock this individual cookie jar in their student's laboratory drawers. The cookie jars being placed in individual drawers avoided the problem of cross contamination between different crucibles and eliminated both the danger of frozen desiccator lids and the student al906
Journal of Chemical Education
Figure 2. Aluminum desiccator stand made from "1.2-mm thick aluminum Sheets. A circular plattorm (diameter 90 mm) with three 35-mm diameter holes to hold sintered glass or porcelain crucibles was fined with four aluminum legs (14 mm X 65 m k ) rivened to the circular platform.
This mlumn represents a consolidation of the Apparatus Review and Inflation Fighters features under a single editorship. Readers will continue to find useful aspects of both. including methods and details of how to Save money by building their own equipment, and information on and evaluations at cunently available equipment. apparatus, and supplies. Novel time-saving or castsaving techniques will also be shared via this feature. Readers interested in contributingto this feature should contact the feature editor.
Each student was asked to buy one jar during the introductory lecture demonstration on safety and laboratory regulations on the first day of class. Aluminum stands for the desiccators were made from ~ 1 . 2 - m mthick aluminum sheets. A local aluminum windowlsiding manufacturer made the stands free of labor cost. A circular platform (diameter 90 mm) with three 35-mm diameter holes to hold sintered glass or porcelain crucibles was fitted with four aluminum legs (14 mm X 65 mm) rivetted to the circular platform (Fig. 2). Additional stands were made in our workshop where legs were attached with small screws and nuts. Indicating Silica Gel, 14-20 mesh, supplied by Fisher Scientific Company is used as desiccant. Each student was sup-
plied with the aluminum support stand and desiccant in the second week of the semester. They had to return the aluminum stand and reactivated desiccant a t the end of the semester and had the option to take the cookie jar home. The following experiments were carried out satisfactorily using these cookie jar desiccators: (1)drying of unknown solid samples supplied for quantitative analyses; (2) drying of primary standards like KHP, K?Cr207.NaCl etc.; (3) estimation of water of crystallization of metal salt hydrates; (4) gravimetric analysis of nickel as bis-dimethylglyoximato nickel (11); and (5) estimation of soluble sulfate, as barium sulfate. In addition to the economy to the department, students liked the idea of homemade apparatus that worked well and was convenient to carry and to store in a drawer.
Volume 60
Number 10
October 1983
907
