To enhance the distribution or backup of data similar to previously distributed or backed up data, to provide similarity testing, and other benefits, a first body of data T of size n is compressed with respect to a second body of data S of size m in-place; that is, the memory containing S is overwritten from left to right so that at no time is more than a total of MAX{m,n}+O memory used. Hydrogen is generated within the gas-generating apparatus and is transported to a fuel cell. The first coating liquid and the second coating liquid react with each other when they are mixed.