The usual rules regulating the employment of iron are to be observed, and the condition of the digestive organs will demand special attention during its employment. Although the influence of arsenic upon rheumatoid arthritis is not uniform, yet as it sometimes proves really useful[261] it should be tried. Like iron, it may prove beneficial in several ways--by improving the quality of the blood, promoting the circulation in the superficial layers of the skin, or exerting some influence upon either the nerve-centres or perhaps upon the vaso-motor nerves of the cutaneous or articular tissues. The last-mentioned suggestion is favored by the circumstance noted by Charcot--viz. that the first effects of arsenic in nodular rheumatism are often intensification of the articular pains, and sometimes the production of redness and swelling where they did not exist before. That author found arsenic without effect or injurious in very inveterate cases and when the disease had appeared at an advanced age. Five to ten minims of Fowler's solution, or of the solution of the arseniate of sodium, which is perhaps less irritating than the former, should be given immediately after meals, and its effects upon the gastric and hepatic functions carefully watched. De Mussy has highly recommended arsenical baths (drachm ss-ij of arseniate of soda to 30 gallons of water), but as the arsenic is not absorbed by the unbroken skin, any improvement which may follow its employment is probably owing to the temperature of the bath or the bath itself. [Footnote 261: As to the value of arsenic in rheumatoid arthritis, see Bardsley's _Medical Reports_, London, 1807; Begbie, _Edin. Med. and Surg. Jour._, 1858; Fuller, _lib. cit._, p. 362; Garrod, _lib. cit._, 3d ed., p. 534; Guéneau de Mussy, _Bull. de Thérapeutique_, t. lxvii., 1864, p. 24; Charcot, _lib. cit._, p. 222.] A similar remark has been made respecting the value of the various {99} thermal mineral baths, natural and artificial, so much employed in this disease.[262] It is neither the nature nor proportion of their mineral ingredients, but the degree of temperature, which constitutes the essential point in the action of a bath. This, if true, explains the almost equal reputation of the many varieties of thermal mineral springs in the treatment of rheumatoid arthritis and chronic rheumatism. It is this that permits the physician to promise the poor patient as much benefit from the employment of hot baths of simple water as of those of New Zealand, Plombières, or Arkansas. [Footnote 262: Vide Niemeyer, _Text-Book Pract. Med._, N.Y., 1867, p. 488; _Traitement du Rheum. par les bains à haute temperature_, par Ch. Aug. Bouther, Paris, 1878.]