A satisfactory method of removing fur or lime deposit from hot-water pipes has not yet been discovered, and it is generally better, and about as cheap, to put in new pipe. One method of removing the lime is to fill the apparatus with some scale-softening compound; but if this plan is adopted, the apparatus cannot be used for some days. Another method is to take out the pipes, make them hot, and then hammer the pipes outside in order to loosen the lime deposit so that it can be shaken out. This is not a perfect method, as hammering does not readily loosen the scale.