73 



RHECMIX. 



RHODIZONIC ACID. 



blood of some substance which acts .is a materla morbl. This sub- 

 stance is not identified, but between the substances of the food on the 

 one hand and the excretions^of the skin and kidneys on the other, there 

 is a wide field for the production of abnormal products, which may be 

 the cause of disease. It has been supposed by Dr. Todd and others, 

 that the real materia norbi is lactic acid in the blood. This, however, 

 is at present problematical, but it is very certain that an abnormal 

 condition of the blood is the most general antecedent of rheumatic 



Cold has been often supposed to be an absolute cause of rheumatism. 

 But this is certainly Dot the case, as out of half a dozen men exposed 

 to the same degree of cold only one may have rheumatism. This 

 MffffK ii also not more prevalent in hot climates, as compared with 

 cold ones, than could be accounted for on the supposition of other 

 causes than cold producing the disease. That cold is an exciting cause 

 when the body is already predisposed there can be no doubt. 



Treatment of rheumatimi. Dr. Haygarth, on being asked what was 

 the beat remedy for acute rheumatism, is said to hare replied, " Six 

 weeks." The sagacity of this reply can be best estimated when the 

 literature of acute rheumatism has been gone through. Blood-letting, 

 calomel, opium, bark, alkalies, iodide of potassium, colchicuin, aconite 

 digitaUX tartarised. antimony, nitrate of potash, brandy and water, 

 infinitesimal doses, have all had their advocates, and in every set of 

 cured cists reported the average duration will be found to be about six 

 weeks. It is not, however, to be supposed that the treatment of acute 

 rheumatism is one of indifference. According to the severity of the 



nptoms and the temperament of the individual the judicious 

 will apply his treatment. The symptoms of disease of the 

 should be watched for with anxiety, and where detected the 

 treatment must be modified accordingly. Blood-letting is now seldom 

 had recourse to. Opium to alleviate great pain and alkalies to act on 

 the kidneys and bowels, and modify the condition of the blood, are 

 recommended by all rational practitioners. Dr. Bennett, of K.lin 

 burgh, speaks highly of nitrate of potass. Local bleeding is occa- 

 sionally of service. In chronic rheumatism liniments over the inflamed 

 joints, with iodide of potassium, and bark, and guaiacum, with other 

 tonics and stimulants, are valuable remedies. Cold bathing and mineral 

 waters are adapted for some cases. 



According to Dr. Elliotson, whether rheumatism be acute or chronic, 

 the treatment should be exactly the same : " You have only to make 

 two distinctions, to ascertain whether it is the inflammatory form of 

 the disease : whether the parts are hotter than they should be, and 

 beat does harm ; or whether the parts are cooler than they should be, 

 and heat does good." In the one case he recommends antiphlogistic 

 measures, and in the other stimulants ; under the antiphlogistic mea- 

 sures, he comprehends bleeding and the administration of colchicum, 

 the latter to be continued till it purges the patient. During the whole 

 time of the treatment cold, lotions are applied to the inflamed joints. 

 In the chronic form of rheumatism the joints are kept hot with 

 flannels and rubbed with stimulating ointments anil liniments, while 

 the ammooiated tincture of guaiacum, beginning with half -dram doses, 

 is given three times a day. Dr. Elliotson also considers that mercury 

 is occasionally useful in both kinds of rheumatism. Lumbago and 

 sciatica are most successfully treated by cupping the loins and the 

 parts over the course of the great sciatic nerve, followed by the appli- 

 cation of busters to the same regions, and a general antiphlogistic 

 regimen. In hemicrania great relief is frequently obtained by the 

 application of heat to the part affected, as in wrapping up the head in 

 flannel. Should the pain evince a tendency to return every evening, a 

 large dose of a narcotic should be administered just previous to the 

 paroxysm, and if not relieved in two or three hours, a similar dose 

 must be repeated ; we are informed that one grain of stramonium fur 

 an adult frequently acts like a charm in this affection. In rhmiu.v 

 talgia, when the parts are not hot, and the pain is not increased by 

 heat, acupuncture and shampooing have been found of great service. 



^ i..-rc the joints are stiff and contracted, from long-continued in- 

 flammation, warm bathing, combined with frequent and persevering 

 exercise of them, have been attended with the most signal success. 



(Sydenham, Ojxra Mtdica, ' Tractatus de Podagra et Hydrope ; ' 



Andral, Anatomic PatlirJi*jii { ue ; C. Roche, l>iftinnnairr de Mtilfeine 



it ilt (,'kiruTfit ; Dr. Barlow, Cyclopadia of Practical Medicine; Dr. 



Elliotson, Practice of Mtdirine ; Dr. Bennett, Principle and Practice 



Fuller, RAtumalitm and JUuumatir (''out.) 



UHK.UMIN. [CiiBTaopiiAXic ACID.] 



1111" (DA 1. 1. INK. [TiuoMXAJUSt] 



KHODANHYDHIC ACID. Synonymous with HYDBOSULMIO- 



CYAXIC A' 



RlloDANOUKX. Synonymous with SfLFHOCTASOOES. 

 ItlK >D F.I iKKTIC ACID. [COXVOLVILIC AciD.1 

 l:Ili>DK<iKKTIN. [Co.xvotvri.rs.] 

 RHODEOKETIXOL. [CONVOLM i.ir...i.n ACID.] 

 RHODKOUKTIXOLIC ACID. [Cosvoi.vruxour Arm.] 



'IHUM (Ro), a metal discovered by the late Dr. Wollaston in 



1803, and named from rkodon (fiotor, a rose), on account of the colour 



of one of its solutions. This metal exists in combination with plati- 



rding to the analysis of Berzelius, the ore of Colombia 



n nr.'.rly three and a hlf per cent., and thai ;i!y 1-15 



. iiii. When tlio gi utter part of tiie platinum and 



palladium have been separated from the solution of the native grains, 

 by the addition of chloride of ammonium and cyanide of mercury, a 

 plate of iron is to be immersed in the residual solution, and by this 

 the rhodium, with small quantities of platinum, copper, and lead, h 

 thrown down in the metallic state. In order to render the rhodium 

 pure, it is first digested in dilute nitric acid, which dissolves the copper 

 and lead, and the rhodium and platinum are then to be dissolved in 

 aqua regia mixed with some common salt, and the solution is to bo 

 evaporated to dryness. By this operation there are obtained thu 

 double chloride of platinum and sodium, and rhodium and sodium. 

 The former is to be dissolved in alcohol, and the latter afterwards in 

 water, when a plate of zinc immersed in the solution precipitate;; 

 the rhodium in the metallic state. The metal thus procured is in tlio 

 state of a black powder, and requires the strongest heat of a wind- 

 furnace, or better the oxyhydrogen blowpipe, for fusion. It is less 

 fusible than platinum. 



Rhodium is white ; has a metallic lustre ; is extremely hard ; specific 

 gravity 12'1 ; and is ductile and malleable. It is not dissolved by any 

 acid or by aqua regia, except when it is alloyed by other metals ; and this 

 circumstance accounts for its being dissolved, when alloyed with pla- 

 tinum, in the native grains of this metal. It suffers no change by 

 exposure to air, either dry or moist. The equivalent of rhodium is 52'1(\ 



Osyt/rH and Rhodium form two compounds. They cannot be made 

 to combine by direct action. The protoxide has not yet been obtained 

 in a state of purity. When finely-divided rhodium, mixed with 

 potash and a little nitre, is heated to redness in a silver crucible, the 

 metal is oxidized, and becomes of a brown colour, and is mixed with 

 potash ; the mass is to he washed with water and then treated with 

 hydrochloric acid, by which hydrated peroxide of rhodium is left, of a 

 greenish gray colour. It contains Ro,O,. When this peroxide is 

 heated, it becomes black, and is then probably converted into pro- 

 toxide. 



Chlorine and Rhodium probably unite in three proportions, but the 

 perchloridc (HOjC'l,) only has been hitherto obtained in a separate state. 

 It was procured by Berzelius by adding silico-hydrofluoric acid to a 

 solution of the chloride of potassium and rhodium, as long as the 

 double fluoride of potassium and silicon was generated, after which 

 the filtered liquor was evaporated .to dryness, and the residue redis- 

 solved in water. The remaining perchloride thus obtained has a dark 

 brown colour, and when heated to redness, chlorine is evolved and 

 metallic rhodium obtained. The aqueous solution of this salt is a 

 fine rose-red colour, whence the name of the metal which it contains. 



This salt forms double compounds, called rhodio-chlorides, with tho 

 chloride of potassium and of sodium. 



>'//'/mr <id Khixlium may be made to combine by heating them 

 together, the metal being in a state of minute division. The protu- 

 mlphide (Ro S) formed fuses at a white heat without decomposition, 

 has a bluish-gray colour, a metallic lustre, and by the action of nitric 

 acid is converted into sulphate of rhodium. Sesqui-iulphide of rhodium 

 (Ro,S,) may be formed by heating the ammonio-chloride of the metal 

 with sulphur, or by heating its solution with sulphide of potassium. 



Haiti of lt/i'xlium. The salts of the peroxide only have been formed. 

 Their general properties are but little known. 



Xitratc of Khodium is obtained by dissolving tho peroxide in the 

 acid : it is of a deep red colour, and uucrystallizablo. 



Fuljihate of Ithotlium is procured, as already mentioned, by acting 

 upon the sulphide with nitric acid. The solution is of a deep red 

 colour, and does not yield crystals. When the caustic alkalies aro 

 added to the solution of this or the other soluble salts of rhodium, a 

 precipitate of the hydrated sesqui-oxide of a greenish-yellow colour 

 i.1 obtained after some time ; the alkaline carbonates produce no 

 effect, nor does sulphurous acid, nor the ferro-cyanide of potassium. 

 Hydro-sulphuric acid throws down sulphide of rhodium; but the 

 hydrosulphates of ammonia and potash produce no immediate 'pre- 

 cipitate. 



Alluyt of Rliodium. When combined with steel to the amount of 

 only two per cent., it gives the steel great hardness without causing it 

 to crack under the hammer. Dr. Wollaston examined several of its 

 alloys, and, on account of its hardness, he suggested its employment 

 for the nibs of metallic pens ; to which purpose it has been applied 

 successfully. It lias not been combined with mercury. 



KHODIZONIC ACID (3HO,C,0, I). In the preparation of POTAS- 

 SIUM, a combination of that element with carbonic oxide is formed in 

 considerable quantities. The composition of this compound is not at 

 present very well understood. In the presence of moisture, however, 

 it assimilates water, and is converted into the potash salt of an acid 

 termed rh'jdizoair. (jiffiaf, a "rose"), from the red colour of its salts. 

 Khodizonate of potash forms oblique rhomboidal prisms of a bluish- 

 green metallic appearance. It is insoluble in alcohol or ether, but 

 readily soluble in water, yielding a deep red solution ; it is inodorous, 

 tasteless, and tolerably permanent in the air. On the addition of 

 sulphuric acid to the potash salt, rhodizonic acid is set free, and may 

 be obtained in bluish-black crystals. 



C'rveonic acid (2 HO, C 10 O,), so called f rom tho yellow colour of its 

 salts, is a product of the action of a temperature of 212 Fahr. upon 

 rhodizonate of potash. From thn potash salt the acid may be set free 

 by sulphuric acid, or, better, Ay It crystallizrs in 



transparent, orange-yellow, inodorous, astringent, and very acid crystals. 



