Rain samples of varying acidities related to the New York City metropolitan area environment for the epochs 1890, 1950, and 1980, as well as two additional variants, were used to study the accelerated reaction with copper, existing patina specimens, and 13 copper compounds (minerals). Cuprite (cuprous oxide), and brochantite (a basic cupric sulfate) formed rapidly under a wide range of conditions. Posnjakite (a hydrated basic cupric sulfate) forms under more limited conditions, sometimes simultaneously with brochantite, but subsequently converts to brochantite. Most copper compounds degrade under low pH (less than 2.5) conditions. The opposing roles of the reaction of copper and patina with precipitation to increase the pH, and the evaporation of the precipitation to decrease the pH were also investigated. While there is considerable evidence that the chemistry of precipitation has changed markedly during the last century as a result of anthropogenic activity, the results show that it is unlikely the changes in the rain composition will have any significant effect on copper patinas. However, the more highly acid fogs do have the potential to produce substantial materials degradation. -- AATA