How would you determine the composition of a crystal obtained from the reaction of CuS, SnS, and ZnS in a sealed tube, without destroying it? The analysis shows the following atomic weight percentages, Cu 26.74 per cent, Zn 15.83 percent, Sn 10.90 per cent, and S 46.54 per cent. Determine the composition of the compound. The crystal was left in air for a week and then analysed again; how might the determined composition change?