Preheat the oven to 200ºF. Line baking sheets with parchment paper.
In the bowl of a stand mixer fitted with the whisk attachment, beat the egg whites with the salt until they just hold soft peaks. With the mixer still running, gradually add the sugar and continue to beat at high speed until the meringue holds stiff, glossy peaks.
Secure the parchment paper to the baking sheets with dabs of meringue.
Spoon a portion of the meringue into a pastry bag fitted with a 1/2-inch-wide tip and pipe bones about 1 inch apart. Add more meringue to the pastry bag and pipe more bones in the same manner on the other baking sheet.
Bake the bones in the oven, switching the position of the sheets halfway through baking, until crisp but still white, about 2 hours.
Turn off the oven and cool the meringue bones in the oven for 1 hour, then transfer them to wire racks to cool completely.