Again, in _chronic rheumatism_ there might, at first view, seem to be frequent exceptions to the rule last above stated; but the cases alluded to are not such. It is often the fact, during chronic rheumatism, that soreness and severe pain are felt, especially under the presentation of the negative pole, thus showing that these points require to be treated with the positive pole. But, in such cases, although the general disease of the system be chronic and negative, these sore and severely painful points have, for the time, risen in their electro-vital condition, and so become acute and positive. But when chronic rheumatism is attended with only a _dull_ pain, and that chiefly under exercise of the parts, and with little or no increase of pain under an application of the negative pole of the A D current, medium strength, and with no swelling, then the pain, the stiffness and the lameness are all marks of the negative state, and the parts must be treated with the negative pole of the A D current, _strongly_ at first, but diminishing in force, from time to time, as the patient becomes relieved. _Alkaline_ affections--those causing excessive alkaline secretions--are electrically positive. _Acid_ or _acidulous_ states are negative. HEALING. For healing wounds, burns, ulcers, irritation of mucous membranes, and cutaneous eruptions, the A D current is by far the best. _Recent_ wounds, contusions and burns are electrically positive. _Old_ ulcers and irritations are generally negative. DIAGNOSIS. To make a correct diagnosis, it is needful to bear in mind the following general principles: 1. Where the organism is in health, the momentary application to the patient of the negative pole of the double Faradaic current B D--the best for diagnostic use--in good medium strength,[D] will be directly felt, yet will cause no pain. Whatever _muscular contractions_ may be produced for the time, they are harmless, and need not be noticed. Wherever the electro-vital fluid is in _excess_, producing hypersthenia--too much vital action--the part is morbidly _positive_; and, excepting sometimes in the stomach and bowels, the B D current, of medium force, directed to that part under the negative pole, will produce _sharp pain_. But where a current of full medium strength can not be felt under the negative pole, there is a morbidly negative state--a deficiency of vital action--a condition of at least partial paralysis--anæsthesia.