development in the United States, learned of the existence of the exudes in what is now known as the oil territory of Mexico. They visited this section, which at the time was largely a jungle, and convinced themselves of the existence of subterranean oil measures. These measures were upon lands which were held in private ownership, under titles dating largely from the time of the Spanish conquest, four hundred years before. In their oil developments they of course, were forced to deal with these private owners, inasmuch as Article 10 of the Mining Law of Mexico at that time provided:
Art. 10. The following substances are the exclusive property of the owner of the land, who may therefore develop and enjoy them, without the formality of claim or special adjudication:
I — Ore bodies of the several varieties of coal.
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IV — Salts found on the surface, fresh and salt water, whether surface or subterranean, petroleum and gaseous springs, or springs of warm medicinal waters.
Shortly after Diaz came into power he induced the government to adopt the plan of granting for a stated term immunity from import and export tariff taxes upon all material brought into the
