Valence Blocks : Notes from the Oesper Collections, No. 56, May/June 2019

Commercial valence block models for use in the lecture hall based on a peg and hole locking mechanism and interchangeable cardboard labels.
Commercial valence block models for use in the lecture hall based on a peg and hole locking mechanism and interchangeable cardboard labels.

Issue 56 describes an unusual type of chemical model known as a valence block that was once used to teach introductory chemistry and which also appeared in chemistry sets in the period 1940-1960.

Click here for all other issues of notes from the Oesper Collections and to explore the Jensen-Thomas Apparatus Collection.

Hans Landolt and the Conservation of Mass : Notes from the Oesper Collections, No. 55, March/April 2019

A highly stippled photo of Landolt’s balance with two of his counterpoised reaction tubes (7) – the one on the left before reaction and the one on the right after reaction.
A highly stippled photo of Landolt’s balance with two of his counterpoised reaction tubes (7) – the one on the left before reaction and the one on the right after reaction.

Issue 55 summarizes, using the resources of the Oesper Collections, the work of the Swiss-German physical chemist, Hans Landolt, on the experimental verification of the law of conservation of mass in chemical reactions. 

Click here for all other issues of Notes from the Oesper Collections and to explore the Jensen-Thomas Apparatus Collection.

A Complete Qual Lab : Notes from the Oesper Collections, No. 54, January/February 2019

The extraordinary
lab bench, chemicals
and equipment for
performing qualitative
chemical analysis offered for sale in the 1902
catalog of the Viennese
laboratory supply house of Lenoir and Forster.

Issue 54 reviews the various chests of reagents and apparatus sold over the last 250 years to private chemists and students wishing to perform qualitative chemical analysis and as highlighted in our collections of apparatus catalogs and monographs.

 Click here for all other issues of Notes from the Oesper Collections and to explore the Jensen-Thomas Apparatus Collection.