Yes, there's no doubt this was Acriflavine. This is a fluorescent dye that commonly contained a similar yellow dye called Proflavine.
Due to a quirk in the naming of the dye, the stuff was sometimes pure acriflavine and sometimes acriflavine hydrochloride, so in theory, a solution could contain all three compounds.
In the 1950's and 1960's it was possible to buy acriflavine powder at most chemist shops to make the liquid yourself and many institutions such as schools used to buy it in this form.