El Bar Americano en España by Pedro Chicote (1927, p.136)

1 tablespoonazúcar en polvo — 1 cucharada de azúcar en polvobase
1 copitadry gin — 1 copita de dry ginbase
agua hirviendo — Used to fill the glass.dilution
1 slicerodaja de limón — 1 rodaja de limóngarnish
nuez moscada rallada — Added after filling.other
  1. Prepare the same way as the Scotch sling, substituting dry gin for whisky.

Defined by Chicote as the same formula as the hot Scotch sling with gin replacing whisky.