How to switch the language by code in flutter-web

I am having problems switching the language in a flutter-web application. I added the required dependencies to the package.yml.

dependencies:
  flutter:
    sdk: flutter
  intl: ^0.16.1

  flutter_localizations:
      sdk: flutter

dev_dependencies:
  flutter_test:
    sdk: flutter
  intl_translation: ^0.17.9

Then I initialized the intl stuff in the MaterialApp.

 [...]
 child: MaterialApp(
        localizationsDelegates: [
          GlobalMaterialLocalizations.delegate,
          GlobalWidgetsLocalizations.delegate,
          S.delegate,
        ],
        supportedLocales: S.delegate.supportedLocales,
        [...]

Here is the code I expect to change the locale.

                Text(S.of(context).language),
                RaisedButton(
                  child: Text("deutsch"),
                  onPressed: () {
                    S.load(Locale('de'));
                  },
                ),
                RaisedButton(
                  child: Text("englisch"),
                  onPressed: () {
                    S.load(Locale('en'));
                  },

Here are two arb files containing the translation.

{
    "language": "Deutsch"
}

{
    "language": "English"
}

Everything compiles and I can access the S.of(context) classes. I am sure I missed something. Since the switching of the language doesn't work either if I start in the Android Emulator.

Switching the system locale in the emulator changes the language.

I would appreciate any help or hints.