FireFox Versions 52 and later no longer support the Java plug-in. Virtual Chemistry Experiments cannot be run on Firefox if the version number is 52 or higher.
Chrome Versions 45 and later no longer support NPAPI, which is required for the Java plug-in to function. Virtual Chemistry Experiments cannot be run on Chrome if the version number is 45 or higher.
Virtual Chemistry Experiments can be run on Internet Explorer up to Version 11.
The Virtual Chemistry Experiments employ Java. Correct operation of Java in the web browser requires careful attention to the following issues.
Either select the Medium security setting or
select the High security setting and enter http://www.chm.davidson.edu as a trusted site.
The Medium security setting no longer exists.
Therefore, it is necessary to select the High security setting and enter http://www.chm.davidson.edu as a trusted site on the Site Exception list.
For more information on security settings, especially as regards Physlets and configuring Java on a Mac, please see the Physlet Physics web site.
The chemistry applets and Virtual Chemistry Experiments web pages were written by David N. Blauch. If you encounter any bugs or technical problems, please send me the following information:
- The URL of the web page containing the error.
- The name and version of the operating system and web browser you are using.
- The version of the Java plug-in you are using.
- The specific settings or circumstances under which the problem occurs and a description of the problem.
I am always eager for new ideas for chemistry applets or web pages and would appreciates any suggestions. Thanks.
Documentation for the chemistry applets is provided for individuals wishing to write their own web pages.
The current version of the chemistry applets and Virtual Chemistry web pages requires a web browser and the Java plug-in (version 1.5 or later is required). The Java plug-in is part of the Java Runtime Environment (JRE). You may check whether Java is installed correctly by visiting the Test Your Java Version page on the Sun web site. In addition to testing the Java installation, you will obtain information on the installed version of Java.
The virtual chemistry web pages displaying three-dimensional content also require Java3D (version 1.5 or later). See the Java3D section below for important information regarding the use of this software.
- Pop-Up Windows
The Virtual Chemistry web pages employ pop-up windows to provide warnings, answers to questions, graphs, and other information. Some experiments will not function correctly if pop-up windows are blocked. Pop-up windows should therefore be allowed for the server hosting the Virtual Chemistry web pages (www.chm.davidson.edu or your local web site).
- Firefox 3.0Tools | Options | Content
To allow pop-up windows from the web site hosting the Virtual Chemistry web pages, make sure the Block pop-up windows box is checked and select Exceptions .... (Alternately, one my uncheck the box, to permit pop-ups from all sites.) Enter the hosting web server (www.chm.davidson.edu or your local web server) in the box under Address of Web Site and select Allow. Click on Close to close the Exceptions dialog and then click on OK to close the Options dialog.
- Internet Explorer 7.0Tools | Pop-up Blocker
Select Pop-up Blocker settings and enter the hosting web server (www.chm.davidson.edu or your local web server) in the box under Address of Website to Allow. Click on Add and then click on Close to close the Pop-up Blocker dialog.
Virtual Chemistry Experiments providing 3D content employ Java3D.
Java3D may be downloaded the Java3D web site.
- InstallationThe Java3D installer will deploy Java3D in all current Java installations.
If Java is upgraded to a new version (e.g.,Java 8), it may be necessary to reinstall Java 3D
The following link tests whether Java3D is correctly installed: Test Java3D
- Memory LimitationsThe default configuration for Java allocates a heap space of 96 MB. Most modern computers can readily provide a substantially larger amount of memory. Java3D is memory intensive and some of the isosurfaces displayed in Virtual Chemistry Experiments are relative large. When insufficient memory is available, the web browser may simply freeze and the web page fail to load. For web pages that download several large virtual reality files, and progress counter may freeze at a specific file (the file that exhausts the available memory). Alternately, one of the following two messages may be displayed on the Java console:java.lang.OutOfMemoryErrorThe available Java heap memory may be displayed by entering m at the Java console. A free memory level at or near 0% indicates the Java Virtual Machine has exhausted its available heap space.
The amount of memory available to Java may be increased in the Java Control Panel. (In Windows, this is found in the Windows Control Panel.) Under the Java tab select Java Runtime Environment Settings. Find the most recent version of Java and enter -Xmx200m under the Java Runtime Parameters. The switch -Xmx200m allocates 200 MB of memory for the Java heap. Although more memory could be allocated if necessary, in my experience 200 MB is sufficient memory for any of the Virtual Chemistry Experiments.
I recommend increasing the memory available to Java applets when Java or Java3D is installed.
When a Java update is applied, check to make sure the runtime parameters have been preserved in the new version.
- Mouse Interaction
Button Action Left rotate object Center zoom control Right translate object
In order to comply with new security restrictions for Java, all Chemistry Applets are now signed.
The Virtual Chemistry Experiments web pages will only operate at a Java Security Level of High if the originating site for the web page (and applet jar files) is a trusted site. The http://www.chm.davidson.edu web site can be designated as a trusted site by opening the Java Control Panel, selecting the Security tab, and clicking on the Edit Site List button. Use the add button to enter the site to be trusted.
Alternatively, one can set the Java Security Level to Medium, in which case it is not necessary to enter the above sites as trusted site. This option provides a lower overall level of security, though.
Programmers using the Chemistry Applets must now include the following parameter in each <APPLET> or <OBJECT> tag:
<param name="permissions" value="sandbox">
Under Java 7.06 and 7.07, Java3D windows fail to repaint when the browser ceases to be the active window. The Java3D
applet window appears white. This problem has been observed under FireFox 15, IE 9, and Chrome 21.
Work-Around: The normal Java3D display can be restored by performing an activity of some sort in the window (rotation, moving, etc).
The original version of the Java3D applets did not identify the correct display device in multi-screen environments, giving rise to the following error:
java.lang.IllegalArgumentException: adding a container to a container on a different GraphicsDevice
Resolution: The current versions of the Java3D applets now correctly identify the active display. If you discover a new hardware configurations that gives rise to this error, please send me the details (firstname.lastname@example.org) (February 2, 2010).
Some of the VCE pages using Java3D may require more than the default 96 MB heap space allocated for Java applets.
In such circumstances, the display may freeze or the Java applet may fail to load. The following error message is typically displayed in the Java console:
Users may enter m at the Java console to check the available memory. A free memory level at or near 0% indicates the Java Virtual Machine has exhausted its available heap space.
Resolution: Increase the amount of memory available to Java. Access the Java Control Panel, and select Java | Java Runtime Environment Settings. Find the most recent version of Java and enter -Xmx200m under the Java Runtime Parameters. This switch allocates 200 MB of memory for the Java heap. Although more memory could be allocated if necessary, in my experience 200 MB is sufficient memory for any of the Virtual Chemistry Experiments.
Physlets (Physics Applets) are small flexible Java applets designed for science education. Data Connections is a component of Physlets that permits inter-applet exchange of data and is used in many of the chemistry applets listed below. For more information on Physlets, to obtain the archives and documentation, and to read the Conditions of Use, visit the Physlet home page. A good introduction to Physlets technology is the Physlets book by Wolfgang Christian and Mario Belloni.
Virtual Chemistry Experiments and associated resources may be used and redistributed for non-commerical purposes without requesting permission from the author. Associated resources include the Chemistry Applets, Equilibria package, and resource files (e.g., VRML or molecular structure files). Derivative works and publications whose results are obtained with these resources should acknowledge David N. Blauch.
Web pages and Chemistry Applets that employ Physlets are subject to the Physlets Conditions of Use; consult the Physlets web site for these conditions. Web pages and applets that require Physlets.jar employ Physlets.
Virtual Chemistry Experiments Home Page
Send comments and feedback to David N. Blauch
Last updated Monday April 24 2017