"The sulphur that is in the samples of copper ore, if burned, will make a sulphurous acid gas, and while it must be carefully used, on account of its noxious and offensive odor, is a most powerful germicide. Or if we take some of the green acid of the copper, and make a liquid of it, and then pour this over common salt we are making what is known as muriatic acid. The vapor of this acid will destroy all germs. The objection to this, however, is, that it has an odor which is worse than the impure or unhealthful gases. In the last samples of ore we brought home, you may have noticed a very black lot of stuff. That was manganese. If we take the muriatic acid, which I have just referred to, and pour it over the manganese, we can make the most powerful agent of all, namely, chlorine."
"Chlorine is used for bleaching, isn't it?"
"That is its great use in the arts; but as a purifier it has no equal. It will decompose every gaseous compound and evil-smelling gas which escapes from decayed animal or vegetable matter."
Harry did not let the Professor forget the matter of the primary electric battery which he had been making preparations for, and after they had gone over the sanitary features of their kitchen, he was anxious to make a start. George was equally insistent, because the question of a better light was ever uppermost in his mind.
"Then here goes for the primary battery. We haven't any glass, nor have we found any rubber lying around, so we can make cells out of them, so what shall we use?" was the Professor's first inquiry.
"Why not use some of these iron pots we made?"
"I am afraid iron would not last very long, with sulphuric acid in them. We should use some non-conductor of electricity."
"What do you mean by non-conductor?"
"That quality in a material which will not allow electricity to pass."
"Then why can't we use clay? Will that conduct electricity?"