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to the fame eminent oculift, friftions once a day over the 

 eye-brow with mercurial ointment, opium being added to 

 it, very much contribute to the abforption of the lymph 

 effufed in the poflerior chamber. 



It is feldom necefTary to continue many days the exhi- 

 bition of mercury ; for fuch is the efficacy of this mineral 

 in producing a removal of the lymph, and clearing away 

 all opacities about the pupil, that in lefs than eight or ten 

 days thefe objefts are generally effefted, and the medicine 

 then may be omitted. 



The form of iritis, ufually named fypMHtic, is unqueftion- 

 ably one of thofe difeafes which does not require more 

 mercury for its cure than the common idiopathic iritis ; and 

 although it was fuppofed by profeffbr Schmidt that it could 

 not be radically cured without removing the conllitutional 

 difeafe, modern experience fully proves, that it may often 

 be entirely and permanently reHeved by freely exhibiting 

 mercury for only a few days. This is another faft tending 

 to confirm the opinions which have recently been examined 

 and promulgated with fo much ability by feveral of our 

 army furgeons, in relation to the curability of all the forms 

 of fyphilis without mercury. For, even in the fyphiHtic 

 iritis, we are not to imagine that the complaint is ilopped 

 and cured by a few grains of calomel, on the principle of 

 eradicating a fpecific difeafe : the thing is more rationally 

 explained by the peculiar efficacy of the medicine in pro- 

 ducing an abforption of the lymph, which thickens the iris, 

 . obftrufts the pupil, and even ferves for the formation of 

 preternatural adhefions, and new opaque membranes deftruc- 

 tive of vifion. Befides the ufe of mercury, however, other 

 means are advifable. When there is fevere pain in the eye 

 with violent head-ache, three or four leeches Ihould be ap- 

 plied on the eye-brow, and a mild purgative adminillered. 

 The nightly attacks of pain, which are fo invariably followed 

 by an aggravation of all the fymptoms, are moil effeftually 

 prevented by rubbing into the part juft over the eye-brow 

 a fmall quantity of mercurial ointment with opium, a fhort 

 time before the pain is expefted to begin, and then covering 

 the eye with a folded piece of warm linen. Generally 

 fpeaking, calomel given in fmall dofes two or three times 

 a day, is the. bell preparation of mercury for internal exhi- 

 bition. 



The iritis which accompanies cutaneous eruptions was 

 thought by Schmidt to be the moft eafy of cure ; local bleed- 

 ings are faid to be in this cafe ilrikingly beneficial. Accord- 

 ing to fome writers, when the eruptions have arifen from the 

 previous abufe of mercury, calomel has not the leaft effeft 

 on the accompanying iritis. But at the London Infirmary 

 for difeafes of the eye, this form of the difeafe, though ori- 

 ginally it may have been caufed by the effefts of a mercurial 

 courfe, is faid to be benefited as much as the other varieties 

 of iritis by the exhibition of mercury ; a circumftance which 

 no mode of reafoning would ever have led us to anticipate. 

 If, however, it be an unequivocal fa£t, the voice of experience 

 muft direft us in praftice, and we muft be filent on things 

 which we cannot explain. 



The beft account of iritis is contained in profefibr Schmidt's 

 valuable work, entitled " Ueber Nachftaar \md Iritis nach 

 Staar-Operationen," 4to. Wien. 1801. Additional inform- 

 ation is alfo publifiied in Beer's " Lehre von den Augen- 

 krankheiten," b. i. p. 450. Wien. 1813. Saunders on 

 Difeafes of the Eye, edit. 3. by Dr. Farre ; B. Travers, in 

 " Surgical Effays," part i. Carmichael in " Obfervations 

 on the Symptoms and Specific Diftinttions of Venereal 

 Difeafes," 8vo. 1818. The Quarterly Journal of Foreign 

 Medicine, N*^ i. contains a well-written analyfis of profefibr 

 Schmidt's work on Iritis ; and at the fame time that we 



ication 

 cannot 



ISO 



acknowledge our obligations to that periodical publi, 

 for every thmg which is valuable in this article, we cam,, 

 refram from exprefling our beft withes for the fuccefs of a 

 journal, the principal objed of which is to make us acquainted 

 with the contents of all the beft modern books which appear 

 on the fubjed of medical fcience in different parts of the 

 continent. 



IRON, in Chemiftry. According to the recent determina- 

 tion of Dr. Thomfon, the black or protoxyd of iron is a 

 compound of 



Iron - . - 100. 



Oxygen - - 28.5 



Hence the weight of the atom of iron will be 35. The 

 red or peroxyd of iron, according to the fame chemift, is 

 a compound of 



Iron ... 100. 



Oxygen - - 42-955 



Or it is compofed of I atom iron + i i atoms oxygen, or, 

 to get rid of fraftions, of 2 atoms iron + 3 atoms oxygen, 

 on which latter fuppofition the weight of an atom of per- 

 oxyd will be 100. 



Iron-Clay. See Mixeralogy, Addenda. 



Irox-Flint. See Mineralogy, Addenda. 



Iron, Meteoric. See Mineralogy, Addenda. 



Iron-Sand. See Mineralogy, Addenda. 



Iron-Stone, Iron-Ore. See Iron-Stone, and Mine- 

 ralogy, Addenda. 



Iron-Stone, Magnetic. See Mineralogy, Addenda. 



IRVINE, col. 2,1. 12, r. In 1811, the burgh and parifh 

 contained 694 houfes, and 5750 inhabitants. 



IRWIN, a townftiip of Venango county, in Pennfylvania, 

 having 357 inhabitants. 



ISAURIA, 1. I, for town r. country. 



ISCHNOCARPUS, in Botany, from iTx>ouJlender, and 

 y.t.(i:o;, fruit. — Brown Tr. of Wern. Soc. v. i. 61. Ait, 

 Hort. Kew. v. 2. 69. — Clafs and order, Pentandria Mona- 

 gynia. Nat. Ord. Conlortic, Linn. Apocinea, Julf. Br. 



Efi". Ch. Follicles two, thrcad-fliaped, divaricated. Seeds 

 hairy at the top. CoroUa falver-ihaped ; throat naked. 

 Anthers not attached to the ftigma. 



l.\. frutefcens. Ait. n. I. (Apocynum /ru/^«;j, fee 

 that article, n. 7. Burm. Zeyl. t. 12. f. I.) — The only 

 fpecies. 



ISLE OF Wight. At the end, add — By the parlia- 

 mentary returns in 181 1, the Ifle of Wight contained 4323 

 houfes, and 24, 120 perfons ; 1 1,955 being males, and 12,165 

 females. 



Isle of Wight, in America, 1. 3, r. containing 9186 inha- 

 bitants, of whom 4041 were flaves in 1810. 



ISLEBOROUGH, 1. 5, r. 583. 



ISLEWORTH, 1. 20, add— By the parliamentary^ re- 

 turns in 181 1, the parifh contained 775 houfes, and 4661 

 perfons. 



ISLINGTON, col. 2, 1. 15, r. 1811 — 15,065—2399. 



ISOCHILUS, in Botany, .<ro,-, equal, and ;^ri>>o,-, a //^, 

 from the proportion of that part to the calyx and petals.— 



Brown in Ait. Hort. Kew. v. 5. 209 Clafs and order, 



Gynandria Monandria. Nat. Ord. Orchidect. 



Eft". Ch. Lip nearly fimilar to the converging petals and 

 calyx. Anther a moveable deciduous lid. Mafles of pollen 

 four, parallel. 



I. I. linearis. Ait. n. I. (Epidendrum lineare ; Jacq. 

 Amer. 221. t. 131. f. i.) — Spike terminal. Leaves linear, ^ 

 emarginate. Stem fimple. 



3 U 2 z.l.proKfer^ 



