In 1932, they began to use a boat to ferry water to the island, and in 1957 a submarine water pipe was laid, but in the early days freshwater was obtained by distilling seawater using coal from the mine. An important by-product of this process was salt, and in the Meiji period, the amount of salt sold sometime exceeded the amount of coal, which was ostensibly the island's principal product. Beside the oldest apartment building (No. 30) stood the chimney of the saltern and the distillery and in photographs taken late in Meiji we can see three chimneys belching forth clack smoke. Coal dug from Gunkanjima contains few sulphates and is good in quality, but there is no denying that carbon dioxide and sulfur dioxide in exhausted smoke damage old reinforced concrete buildings like these. However we have no data to confirm that smoke caused damage to the buildings on Gunkanjima.