I believe that this is a primary source document
<span>Soon after gaining independence from Spain in 1821, Mexico opened its northern coastal region of California to foreign trade. American vessels from the east were soon engaged in lucrative commerce with the Californios, Californians of Spanish or Mexican descent. Offering such necessities as cooking utensils and boots, as well as luxuries such as brandy, the Americans reaped profits of 200 to 300 percent. In exchange, the Californios exported cowhides produced on their vast coastal ranches.</span>
It outlawed the discriminatory voting practices adopted in many southern states after the Civil War, including literacy tests as a prerequisite to voting. This “act to enforce the fifteenth amendment to the Constitution” was signed into law 95 years after the amendment was ratified.
Heat cause thremal has to do with heat