_The posts_, with which the conducting-cords are to be connected, are arranged in a row near the front of the helix-box, and are marked A, B, C, D. Either two of these posts may be used to obtain a current; and since they admit of six varying combinations, six different currents are afforded by the machine, viz: the A B current, the A C current, the A D current, the B C current, the B D current, and the C D current. Whichever current is used, it may always be known which of the two posts employed is the positive and which the negative, by observing the letters stamped upon their tops. The one whose letter comes first in the order of the alphabet is positive; the other is negative. Also, the one standing towards the left hand is positive, and that at the right hand is negative. _The qualities_ of the several currents are stated in a descriptive paper on the inside of the lid of the machine, which see. It will there be found that three of the currents--viz, the A B, the A C and the A D currents--are _electrolytic_: that is, dissolving by electric action. These electrolytic currents require to be used--one or another of them--whenever any chemical action is needed; as, in decomposing or neutralizing _virus_ in the system, destroying cancers, reducing glands when chronically enlarged, removing tumors or other abnormal growths, and in treating old ulcers and chronic irritation of mucous membranes. The other three, being Faradaic or induction currents, and having no perceptibly chemical action, are used where only change of electro-vital polarization is required. These Faradaic currents differ from each other in respect to being _concentrative_ or _diffusive_ in their effects, and in their _sensational_ force. B C is concentrative and delicately sensational. C D is also concentrative, though less so than B C, and is more strongly sensational. B D is diffusive, and the most energetically sensational of the three. POLARIZATION. It may be proper, in this place, to spend a few words upon electrical polarization in general.