In a large bowl, sift flour, salt, and baking powder together.
In the bowl of your electric mixer, beat butter, shortening, and sugar until fluffy. Stop the mixer and scrape down the sides. Mix to combine.
Add eggs, one at a time, beating well after each addition.
Add the vanilla extract to your milk. Then add the milk mixture and flour alternately, beginning and ending with flour mixture. Stop the mixer and scrape down the sides. Mix again to combine.
Pour half of the batter into the prepared tube pan. Return the bowl with the remaining batter in it to the mixer stand and add the orange gelatin. Mix until combined, but don't over mix. (You also fold the gelatin in by hand.) Pour the orange batter over plain batter and smooth the top.
Bake for 1 hour 20 minutes. The cake is done when no crumbs or dry crumbs remain on a wooden pick when inserted in the thickest part of the cake.
Cool in the pan on wire rack 20 minutes before inverting on a platter to cool completely. Make sure it's cooled completely before frosting and covering.
Sift the powdered sugar. In a mixing bowl, whisk the powdered sugar with cream soda until smooth. Drizzle over cake.
The cake will be good 4 or 5 days in an airtight container on the counter. After that, it will start drying out somewhat.