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Analyzed Quantitative Unknowns
A wide variety of readily available Thorn Smith Quantitative Unknowns include:
Gravimetric unknowns such as Soluble Chloride, Soluble Sulfate, Ferrous Ammonium Sulfate
Oxidimetric unknowns such as Soluble Oxalate, Arsenious Acid, and Ferrous Ammonium Sulfate
Acidimetric unknowns such as Acid Potassium Phthalate and Soda Ash
Complexometric unknowns such as Copper Oxide (particularly recommended), Calcium Carbonate and Magnesium Sulfate
Other unknowns such as Brass, Steel, Silver Alloys and numerous others.
Varieties of Student Quantitative Unknowns (Series)
What Is A Series?
Most batches of active materials are divided into as many as 25 lots. These lots are then carefully measured and portioned with the differing percents of inactive ingredients. This procedure is what is referred to as a series of student unknowns. For example, iron oxide is produced in a series of 25 unknowns with each lot carefully prepared, analyzed, recorded and then inventoried.
Filling Orders For Series
It is our policy to send one of each series when filling your order. If you order 18 student unknowns of iron oxide, you should receive 18 varieties depending on availability and balancing of our inventories. At certain times we may even have more (sometimes we may have more; sometimes less) than the 25 listed varieties, due to residual inventories from previous series after a new series is produced. In these cases, if you should order 33 iron oxide student unknowns, it is conceivable that you will receive 33 varieties without duplicates. This kind of service to you is automatic without your need of requesting it. In any case, please call to verify quantities.
Our standard practice is to provide a variety of percentages when filling unknown orders. When the requester places an order, we automatically send a variety of lots. We do not duplicate lots unless it is specifically requested by the buyer, or availability is such that we cannot give all separate lots.
When the requester asks for specific lots it depletes our inventory unevenly. We can accommodate requested lots only if they are available. There is a Lot Specification Charge added to each order when specific lots are being requested. This charge is $10.00.