Auction # 2424 ARGENTINA: Special July auction

TEST COVERS: 2 envelopes that were possibly used in instructional activities of the Post during the 1910 expositions in Buenos Aires, both seem to have had some label simulating the post, they also bear machine postmarks of 15/AU and 7/SE, and their "postage" has been removed. I found them in a very old mail archive, very interesting!