Mill I |lll|lll|l| I I I IM ■ ■ § ;■ . ;| ;!;;■; .•.•:".:--siifij!tcr:ii,r; ■: WQ& ■/m^m niHa:nr:n!--::!:'t'=-i":::';-: ■ ''i^'Hi ■ *^ :;!'::!:t:' Jiii. li:. ■l.;-'.'-. • • ■ . r Wit1".'. ' i"':-/:j;:: :■■■ \>: ^-;;'■::!■ ■J/':l;y ''■llf'ife!' ''^M '-'r' Wm&m ; '■■■;■> ■ ■- y ■■■"<&,..... 976 NATIONAL LIBRARY OF MEDICINE Washington Founded 1836 U. S. Department of Health, Education, and Welfare Public Health Service '() CHEAP BOOK STORE, Q ONo. 158 North Second Street/) h corner of New. Philad'a. 0 OF THE NITROUS FUMIGATION. Je ne connois pas de theorie qui puifle decider une ques- tion qui interefle la vie des hommes ; il ni a que des expe- riences faites avec foin, et multipliees a I'infini, qui doivent fervir de loi en medicine. THE EFFECT OF THE NITROUS VAPOUR, IN PREVENTING AND DESTROYING CONTAGION; ASCERTAINED, FROM A VARIETY OF TRIALS, MADE CHIEFLY BY SURGEONS OF HIS MAJESTY'S NAVY, IN PRISONS, HOSPITALS, AND ON BOARD OF SHIPS'. WITH AN INTRODUCTION Re/peeling the Nature of the Contagion, WHICH GIVES RISE TO THE JAIL OR HOSPITAL FEVER; THE VARIOUS METHODS FORMERLY EMPLOYE PREVENT OR DESTROY THIS. B Y *S JAMES CARMICHAEL* SMYTH, M.D.F.R.S. FELLOW OF THE ROYAL COLLEGE OF PHYSICIANS, AND PHYSICIAN EXTRAORDINARY TO HIS MAJESTY. PHILADELPHIA: PRINTED BY BUDO AND BARTRAM, FOR THOMAS DOBSON, AT THE STONE HOUSE, N° 41, SOUTH SECOND STREET.--1799. « [ v ] TO THE RIGHT HONOURABLE EARL SPENCER, &c. &c, &c. My Lord, J\ S moil of the following trials with the nitrous vapour were made in confequence of an order iflued by your Lordfhip, and the other Lords Commiflioners of the Admi- ralty, for employing it in the navy; it muft afford you fome fatisfaclion to obferve, that fuccefs has followed your Lordfhip's decifion on this, as on more important occafions: nor can you be furprifed that I mould be de- firous of prefixing your name to a publica- tion, which owes its exiflence, in great mea- fure / Vi DEDICATION. fure to yourfelf. I have now no occafion to folicit your Lordihip's recommendation of a meafure, which a convi&ion of its utility has already led you to adopt; but I have to thank you, which I do moft fincerely, for the attention you have given to the fubject, and for your candour and politenefs to the Author.« I have the honour to be, With the moil perfect confideration and refpeft, My Lord, Your Lordihip's moll obedient, And much obliged fervant, JAS CARMICHAEL SMYTH. Earl Spencer. PREFACE. PREFACE. J. HREE years have now almoft elapfed fince I published an account of the experi- ment made with the nitrous fumigation on board the Union hofpital fhip, and of the fimilar trials made at the fame time on board fome mips of the Ruffian fquadron. The accurate and candid narrative of this bufiiiefs, given by thofe gentlemen, who undertook the conducting it, proved in the clearefl and moil unequivocal manner, to every unbiafled mind, not only the power of the nitrous vapour in deftroying contagion, but the fafety with which it might be em- ployed : fuch, however, is the force of pre- judice, as to render doubtful even the evidence of our fenfes. A confiderable increafe in the number of deaths, amongft the Ruffians, hap- pening [ viii ] pening in the month of January, a rumour was immediately propagated that this mortal- ity was occafioned by the nitrous fumigation, which, though it might feem harmlefs in the beginning, poflefled fome latent deleterious quality that in the end proved fatal. Hearing of this by accident, and knowing how difficult it is to remove impreffions that have once laid hold of the public mind, I made application to Lord Spencer, and to the other Lords Commiffioners of the Ad- miralty, requefting that they would have the goodnefs to appoint proper perfons to inves- tigate this matter fully, and to report to their Lordfhips the reiult of their inquiry. My requeft was complied with, and the report of thofe gentlemen proved in the moft fatisfac- tory manner, that the rumour was a direct mifreprefentation of the fact; that the mor- tality amongft the Ruffians was owing to different caufes unconnected with the fumi- gation; that thofe who had been longeft expofed [ «■] expofed to it enjoyed the bell health; and that not a fingle inflance could be adduced of any bad confequence which could fairly be imputed to the nitrous vapour, during the three months it had been employed. This objection being removed, another flill prefented itfelf. It had been faid, and faid with truth, that the vitriolic acid, in a con- centrated flate (commonly called oil of vitriol) was a dangerous article to be taken on board of fhip, as there had been inflances of fhips let on fire by it; and that this accident actu- ally happened to two tranfports of Admiral Chriftian's fquadron. The fact could not be denied ; but the fame objection applied, and with flill greater force, to the ufe of fire, of gun-powder, and of ardent fpirits; all of which are, without doubt, extremely hazard- ous m the hands of ignorance or of raihnefs; but which, when their effects are known, with the proper means of obviating them, may be employed with as much fafety as air or water. B To ( X ) To do away, however, every poffible objec- tion on this head, I had proper cafes made, one for the mineral acids, and another for the purified nitre, with the inilruments neceffary for the fumigation. The mineral acids were firfl put into flrong glafs bottles, fitted with ground glafs Hoppers, fecured with wire; thefe were placed in a cafe lined with copper covered with an amalgama of tin and lead, with divilions of the fame; the interflices of the divifions were afterwards filled up with faw-dull: by this means the bottles were fe- cured from breaking, and even if that fhould happen, the acids could not efcape, nor affect the lining of the cafe; fo that every danger which could pofTibly arife was completely forefeen and prevented. A cafe fimilar to the former, but entirely of wood, with divifions of the fame, was made for holding the nitre: the nitre was put into four flone or earthen jars, adapted to four divifions in the cafe, which had a fifth divifion alfo, the whole width ( xi ) width of the cafe, for containing the pipkins, cups, meafures, and other inflruments necef- fary for the fumigation. Thefe cafes I fent to the Admiralty for the inflection of their Lordfhips, and as they met with their appro- bation, their Lordfhips ordered fimilar cafes to be made and fent on board every fhip in his Majefly's fervice; and that the materials neceffary for the nitrous fumigation fhould be fent alfo to the different naval hofpitals and prifons. I need hardly add, that the greater part of the experiments and trials which I have now the honour to lay before the public, are the refult of this order of the Lords Commiffioners of the Admiralty. Many of thofe communications have been fent to me, as will prefently appear, by the Board for fick and wounded feamen ; but for feveral, by far the mjfl important, I am in- debted to the friendfhip of Dr. Johnfton, one of the Commiffioners of that Board, a gentleman whofe humanity and active zeal in the ( *ii ) the fervice of his country are well known, and whofe character Hands too high in the public opinion to receive any addition from my praife. He was fortunately one of the extra- Commiffioners at Portfmouth, when fome of the firfl trials were made with the nitrous fumigation, and from the happy effects pro- duced by it, became a warm advocate in its behalf; a circumflance which firfl introduced me to the honour of his acquaintance. As for the gentlemen themfelves who have made the trials with the nitrous fumigation, I fhall only obferve, that they cannot be fuf- pected, in the reports or opinions they have delivered on this fubject, to have been influ- enced by any partiality to me ; as, excepting Captain Lane of the navy, I had not the ho- nour of the flightefl acquaintance with any of them ; and feveral, plough they had heard of the experiment on board the Union, had never read a word I had written on the fub- ject. It appears, however, very evident from their ( xiii ) their letters, that there are amongft them men of obfervation and experience, and if we may judge from the important flations in which fome of them are placed, they are men of high and refpectable characters in the fervice. Refpecting their obfervations, I may fairly fay, that in general, they carry with them the internal evidence of truth. But I fhall exa- mine this fubject more particularly, after having prefented the public with the letters and communications of the authors. Of the Introdudion I have only to remark, that it contains thofe general obfervations on the jail and other putrid contagions, with the ufual means of obviating thefe, formerly publifhed in the Treatife on the Fever at Winchefter; and now republifhed, from a wifh to make them more generally known, efpecially to thofe perfons who are likely to be placed in fimilar fituations, or engaged in fimilar enterprifes. It does not fall to the lot of every furgeon, or even phyfician, to the navy ( xiv ) navy or army, to have turned his attention to this fubject in the manner I have done, nor to have had the fame means or opportunity of information. The chief object of my life has been to render my profeffion, and the exercife of it as beneficial as poflible to mankind; my endeavours, however, to bring to perfection, and into general ufe, the prefent difcovery, have been chiefly animated, and I am not afhamed to confefs it, by the defire of render- ing an important fervice to my country. She, as the great maritime power in Europe, is the mofl likely to derive, and I flatter myfelf, will derive the mofl effential benefit from my labours. Chart Parentes, Chart Libert, Propinqui Familiares: fed omnes omnium Charitates, Pa~ tria una compkxa eft. CONTENTS. Page Introduclion - - - - 17 Experiment on board the Union, &c. 49 Letter from David Pat erf on, Efq. Surgeon to For- ton Hofpital - - 95 Three Letters from Mr. MlGrigor, Surgeon to the SSth Regiment, at Jerfey 120 Three Letters from Mr. Hill, Surgeon to the Sin- cerity Hofpital Ship, Langstone Harbour 129 Letter from Mr. Griffin, Surgeon to Forton Hof- pital - 138 Letter from Mr. Glegg, Surgeon to the Defiance Man of War - - 143 Letter from Mr. Magennis, Surgeon to the Hofpi- tal at Norman Croft - - 145 Letter from Mr. Snipe, Surgeon to the Naval Hofpital at Yarmouth - 149 Letter from I. Blatherwick, Efq. - 153 Letter from Captain Lane, Far ham - 154 Letter from Alexander Brown, Efq. Sqrjgeon of the Royal Sovereign - - 156 Letter from Mr. John Drew, Surgeon of the Unite 157 Extracls from Letters or Journals of Surgeons of the Navy, tranfmitted by the Board of Sick and Hurt - - 159 Extracl of a letter from Dr. Withering, of Bir- mingham, to Dr. Duncan, of Edinburgh 164 Two Letters from Dr. Carmichael Smyth, to Dr. Percival, of Manchester - ibid. Conclufion - - - 169 Tables. INTRO- Tb: Reader is requested fo examine these Tables with Attention, as they afford, perhaps, the most complete Evidence, of a Medical FaB, that ever was presented to the Public. Office for Jich and wounded Seamen, EsV. A Weekly progreffive State of the Sicknefs and Mortality among the Spanifh Prifoners, confined in the King's Houfe, at Winchefter, from the flrft Appearance of the Jail Diftemper, until the 8th of July, 1780. A Return of the Attendants on the Hofpital, or Per- fons belonging to the Ship's Company of the Uni on, who were attacked with the Contagious Fever, from the 3d of September, 1795, to the 10th of February, 1796. (Signed) A. BASSAN, Surgeon of the Ship. Date of Weekly Accounts Number of Spanifh Prifoners. * The time of Dr. Carmichael Smyth's going to Winchefter. A Weekly Return of the Patients in Forton Hofpital, &c. from the 16th of October to the 26th of December, 1796. By D. Paterson, Efq. Surgeon to the Hof- pital. Before the Nitrous Vapour was ufed Higheft Number in the Hofpital j I 223 2 372 1 37i 4 369 5« After the Nitrous Vapour wa3 ufed. Before the Nitrous Vapour was ufed. Higheft Number in the Hofpital Number dif- charged 34" 332 342 34° 486 539 27 7 63 128 -a t3 S S I" Quality Nurfe Ss 1 ft Mate Nurfe Helper Nurfe Marine Wafher-wo. Ss 1 ft Mate Nurfe Ab. Nurfe 2d Ss Mate Ab. Marine Nurfe Wafher-wo. Marine Sept. When feized ~6 7 9 15 18 20 22 24 29 6 6 Ab. Marines Marines Ab. Marine Wafher-wo. OcT:. Nov. 14 22 22 22 2 4 4 10 10 17 17 20 2C 24 1'otal 30 Recovered Dead Sep. 24 Sep. 28 oa. 1 — 15 — 11 A Monthly and Daily Return of the Convicts attacked with the Jail-Fever on board the Hulks, and received into the Since- rity Hofpital Ship in Langftone Harbour, from the 6th July to tlie 26th Dec. 1798. By S. Hill, Surgeon to the Hofpital. Dec. 4 Nov. 24 T. uncertain 23 After the Nitrous Vapour was ufed. Quality (When feized Nurfe Marine Dec. 25 ---- 26 Recovered f Recov. in \ a few days Dead Jan. 6 Total On the evening of the 15th of October we began to fumigate the hulks, and continued to do fo every day to the 20th of November, (the oth and 10th of this month excepted;) on the 20th, the fumigation was difcontinued, but refumedon the 26th, and continued without interruption to the nth of January, 1799, though on the a6th/>f December the ficknefs had entirely ceafed. ; •N. B. On the 26th of November the fliip was fumigated fov'l the firft time, and the fumigation repeated twice a day till the: [H] On the lift of November, eight perfors ill with t^ ;,'i f j 17th of December; from that time to the 26th of December Ifentery, were received into the hofpftal, from on Wd *£ HTfl "* 1' i7' ony once; but from the 26th of December to the 10th ofi'tany-bay fhip,outward-bound; dJo^mSl! T^ Februar^twice a day, as at firft. |! {Je J^ a„d five on the l'9th of DeceX in aU fwen yfo'u^ a INTRODUCTION. Refpecling the Nature of the Contagion, which gives rife to the Jail or Hofpital Fever. JL HAT we may be able to form a more accurate judgment of the nature of the contagion, which gives rife to this fpecies of fever, we (hall examine it in four different points of view. In the fird place, how it is generated ; 2dly, in what manner it is propagated, with the circum- ftances more or lefs favourable to its communica- tion ; 3dly, its effects on the human body j and, 4thly, the means of weakening its virulence, or of entirely deftroying it. Whoever has confidered contagious fevers with that attention which the importance of the fubject demands, mutt have obferved, that they are of two very diftinft kinds or *claffes. The firfl may pro- perly enough be called fpecific contagions, as they do not arife from any general quality, or procefs of nature, with which we are acquainted ; and, as they have a peculiar origin, they excite difeafes of a peculiar kind ; differing in many refpe&s from every other, but in nothing more remarkably, than in this, that the peculiar difeafe can only take place once in any individual: and there are fome perfons, C in * This diftin&ion feems fo extremely obvious, that we fliould hardly fuppofe it could cfcape the obfervation of any one who had at all reflected on the fubjc.fr, and yet I do not know any medical writer who has made it. [ 18 ] m whom this contagion never can produce any mor- bid fymptom. The number of thofe peculiar or fpecific poifons is not yet afcertained ; but the fmall- pox and mealies are evidently fuch to man, and there are others peculiar to certain animals. The fecond clafs of contagious fevers, may be named general contagions, as they arife from a gene- ral caufe ; or they may be named putrid, as they will be found, in every inflance, to be the refult of putrefaction, one of thofe general fermentative pro- ceffes, to which water as well as all vegetable and animal fubflances, under certain circumllances, are liable. That the contagion, or miafma, of the jail or hofpital fever derives its origin from this fource, admits of every fpecies of evidence which a matter of fact and of obfervation can do. It is well known, that this difeafe is conflantly produced where a number of people are fllut up together in a clofe place, without the greatefl at- tention to cleanlinefs, and a renewal of air. That all the excretions of the human body have made a certain advance or progrefs towards putridity, and when placed in circumllances favourable to putre- faction, foon become highly putrid. That of all the human excretions, none is more highly ani- malifed, or more fufceptible of becoming putrid, than the perfpiration or vapour iffuing from the fur- face of the body and lungs. That even the perfpi- ration of vegetables, confined under fimilar circum- llances, becomes putrid, and in a high degree noxi- ous to man : a fortiori then, we may conclude, that animal perfpiration will more quickly undergo a fimi- lar alteration, and mufl prove flill more noxious. We obferve, that the contagion, refulting from animal perfpiration, fhews its baneful effects more fuddenly, and more forcibly, in proportion to its quantity, r. '9 ] quantity, and to its being placed in circumflances the mofl favourable to putrefaction; confequently, in proportion to the fize and clofenefs of the place, the temperature* and moiflure of the air, and the addi- tional or acceffory putrid matter with which it is combined. We obferve, likewife, that the formation of this contagion is prevented by caufes that renew the air, and carry off the perfpiration, or prevent its ten- dency to putrefaction. And, it may be mentioned as an analogical proof, that a contagious vapour, differing only in degree of virulence from the human miafmata, is conflantly produced from water alone, or from wa- ter mixed with vegetable and animal matters, when expofed in fufficient quantity and under circumflan- ces favourable to putridity ; but the feptic nature of the jail contagion will be farther iHuflrated, by what we have to notice of its effects on the human body3 * It has been, alledged in objection to this, that the jail fever is more frequent in our prifons in winter than in fum- mer. The fad I can neither confirm nor deny, but admit- ting it in its fullefl extent, it by no means invalidates the opinion I have endeavoured to eflablifh. The cold of our winters is feldom fo fevere, at lead for any length of time, as to freeze the moiflure of the atmofphere, efpecially with- in-doors, and therefore, I run no rifk of contradiction, when I affirm, that in general, the moiflure or water diffufed in the atmofphere, is much greater during the winter, than during the fummer months ; but the cold, though not in general fufficient to dry the air,«is fufficient for thofe confin- ed in the cells of prifons to endeavour to exclude it, although by excluding it, they muft prevent the renewal of the air, and breathe more their own baneful atmofphere. Cold has alfo the effect of making people in their fituation, lefs atten- tive to cleanlinefs, and of inducing lazinefs and debility ; all of which circumflanccs, when taken into the account, will be found greatly to counterbalance the difference of tempe- rature. [ « ] body, and of the methods of dcflroying it, or of rendering it harm!els. Of the Wanner in which Contagion is communicated. Every perfon knows that contagious fevers, whether fpecife or putrid, are ufually propagated by an immediate communication with the fick, either by contact or contiguity. ' How far the con- tagious atmofphere extends, is impoffible to afcer- tain, as this mufl admit of confiderable latitude"*, according to the virulence of the difeafe, fituation of the fick, feafon of the year, flate of the atmof- phere, Sec. My ingenious and refpectable friend Dr. I la) garth is of opinion, and indeed has fhewn, that in the fmall-pox it is much more limited than was apprehended. But it is not only from a direct communication with the fick that contagious fevers are propagtted; unfortunately, the perfons and clothes of thofe who remain long in a contagious atmofphere, and the excretions of the fick, are capable (even when conveyed to a great diflance, or preferved for a length of time) of producing the fame mifchief as an immediate communication with the fick themfelves. Of this fact the examples are fo numerous as to put the matter beyond the pofli- bility of a doubt. Here again, the opinion of my friend Dr. Haygarth differs from the opinions formerly entertained by phyficians. For, though he admits, that the variolous matter, and* the more fenfible excretions of the lick, are capable of com- municating the difeafe, and, If clofe fhut up, of retaining that power for a long time, he does not think, that the contagious vapour, immediately arifin? o * This fuller the reader v ill find treated more fully in two Lexers aJJrcfied to Lr. lVrcival, of M^uJiefter. [ 2' ] arifing from the fick, can be retained by the clothes of thofe confined in the variolous atmofphere, or by the furniture in the chambers of the fick, fo as to communicate the difeafe to fuch as have not themfelves been immediately expofed to it. No one can have a greater refpect for the opinions and obfervations of Dr. Haygarth than I have, as no perfon is better acquainted with his candour and accuracy. I readily agree with him, that the dread of thofe terrible difeafes, and the natural fears of men, have poffibly magnified the danger beyond reality ; that the rifk of propagating the contagion in this manner is by no means fo great as had been fuppofed ; and that phyficians, or even apothecaries, are feldom fo long expofed to this atmofphere, as to be in great danger of conveying the contagion elfewhere ; but I cannot go fo far as to believe that the perfons, and efpecially the clothes of nurfes or afliilants, who are conflantly confined in the chambers of the fick, fometimes not very well ven- tilated, will not imbibe the contagious vapour to fuch a degree, as to be capable of communicating it, efpecially where they have a direct or immediate intercourfe with a perfon fufceptible of the difeafe. But, putting the fmall-pox and other fpcc'ific conta- gions out of the queflion, that the jail diflemper and other putrid contagions are frequently conveyed in this manner, cannot be denied. Indeed, wherever a vapour can be diflinguifhed by the fmell, we have the demonftration of our fenfes for what a length of time, not only clothes, but furniture, and even the boards and walls of houfes will retain it: there- fore, in refpect to the contagion of the jail or hof- pital fever, we may fafely affirm, that it affects not only thofe who are immediately expoied to the origi- nal atmofphere, but that this contagion may cer- tainly be communicated by the clothes of perfons who C « ] Tvho have for any length of time been confined in it j and, what is flill more furprifing, even when the perfons thcmfelves have fuffered no injury, nor had any difeafe in confequence of fuch expofure. This fact being afcertained, we cannot wonder if thofe who are feized with the jail fever, owing to fuch communication, mould during their illnefs generate a contagious vapour ; but, however para- doxical it may appear, I have never obferved that the fick propagated the difeafe fo readily, as the bodies and clothes of thofe who, though well, had been long confined in the original atmofphere. From my own experience alfo, I am led to conclude, that there is little riik of receiving the contagion from dead bodies, even from differing them, pro- vided the furgeon does not cut himfclf during the diffedtion, the confequence of which has generally proved fatal. There are feveral other circumflances, worthy of notice, that increafe or diminifh the facility with which contagion is communicated. Unlefs where contagion is very powerful, it is feldom propagated in the open air; I knew only one inflance of this at Winchefler. It is much more certainly commu- nicated in a room, and efpecially if there is a cur- rent of air, from the contagious perfon to others capable of being affected. A moifl atmofphere* is alfo more favourable to the communication of con- tagion than a dry one. A contagious perfon be- comes greatly more fo, if his clothes are wet, and his * Moiflure appears not only neceffary to the production of putrid contagion, but it would feem to be the medium alfo by which it is communicated ; it is well known, that the plague ceafcs, in Syria and Egypt, during the preva- lence ol certain drying winds; and its almoft entirely difap- peanng during the winter, at Mofcow, was probably owing to the fame caufe ; viz. the drynef* of the atmofphere. C »3 3 his body heated by exercife, fo as to be in a flate of perfpiration. Thofe molt fufceptible of contagion are, young perfons, particularly if they come di- rectly from a pure air into the infected atmofphere ; perfons whofe minds are oppreffed with fear or anxiety; or who have been weakened by previous illnefs; even thofe who have been fatigued, or are falling, more readily than others whofe flrength has not been impaired, or which has been again re- cruited with food. It has been farther remarked, that perfons who have iffues are feldom affected by contagion. Of the Effecls of putrid Contagion on the human Body. Putrid matter, in whatever way generated, if in fufficient quantity, has always fome deleterious effect; or, in other words, acts as a poifon upon the body. It is true, that the human flomach, and flill more remarkably, the organs of digeflion of certain animals, have the power of counteracting the feptic tendency; but this power, in our flo- machs at Ieafl, is very limited ; and when any mat- ter, whether generated in the body or introduced from without, has acquired a degree of putridity beyond this, it occafions naufea, vomiting, purging, great oppreffion at the region of the flomach, and often a fever, either of the intermittent, remittent, or more continued kind. Putrid matter, directly introduced into the fyflem by means of a wound, caufes fwelling and inflammation of the lymphatic glands, often terminating fuddenly in gangrene, along with the fymptoms of a fever, greatly refem- bling the hofpital or jail fever: the fame proflra- tion of flrength, tremors, anxiety, headach, and delirium j [ 24 ] delirium; with the fame irregularity in the pulfe, and, if the difeafe continues, it induces thofe ap- pearances of the fkin, hemorrhages, and other fymptoms, that indicate a relaxation of ihe folids, and refolved crafis of the blood. The fevers that arife in confequence of expofurc to putrid vapour or contagion, affume a variety of types and forms, according to the various circumllances of combina- tion, degree of putridity, feafon of the year, con- flitution of the patient, &rc. But they, as well as the preceding, will be found to have many fymp- toms in common, and fimilar to the jail and hofpi- tal fever: and in reality all the fevers of this clafs, from the flightefl vernal intermittent to the true plague, are in my opinion only different fhades or varieties of the fame difeafe, and productions of one common caulc, viz. putrefaction. I fhall not, how- ever, profecute this fubject farther at prefent, as I have treated it more fully in another work, which, fhould I hereafter have leifure to complete, 1 hope to render not altogether unworthy of the public eye. The contagion then of the jail or hofpital fever, may juflly be confidered as one of the mofl fubtil and powerful vapours of the putrid kind ; and, con- fequently, its immediate and deflructive effects upon the body, are not to be wondered at. In ordinary cafes of fever, the vital principle is roufed into ac- tion, and Nature is commonly fufficient of herfelf to remove the morbid caufe; but here, as in the real peflilence, the contagion introduced into the body, feems to act as a narcotic poifon upon the heart and nervous fyflem, fuppreffmg the principle of life, in- flead of roufing it to the conflict. In this diflemper therefore, where nature can do fo little, and even art, unlcf* immediately called to her aflifknce, is equally unav^mj, it is of the mofl confequence'for us C *5 ] us to know whether the contagion cannot be pre- vented or deflroyed. Of the Means of preventing^ and of destroying the Jail Contagion. As we are perfectly acquainted with the caufes of the jail contagion, we could certainly prevent its formation, provided the means of doing fo were al- ways in our power; but as we cannot command thefe, our next object is to endeavour to correct, or deflroy it, when formed. As a knowledge of the nature and origin of the jail contagion naturally led to the proper and effectual means of correcting or * deflroying it, fo, on the other hand, the means that have been fuccefsfully employed to deflroy it, afford the mofl convincing evidence of its true nature. The various means hitherto employed for deflroy- ing contagion, may be arranged under two diflinct heads, or claffes, viz. the Phyiical and the Chemical. All contagions, whether fpecific or putrid, are either checked or completely deflroyed, by the ex- tremes of heat and cold; and from a free expofure to air and water, are fo diluted or diffolved, as to lofe their noxious quality. Heat and cold then, with air and water, may be looked upon as phyfi- cal agents, which, under certain circumflances, are effectual in blunting or deflroying contagion. A de- gree of heat, nearly that of an oven, is found ne- ceffary for the complete deflruction'of contagion, but as this degree of heat is incompatible with ani- mal life,* its application is folcly confined to the D purifying * A great heat, like that of an oven, fuch as would prove definitive to all animal life, effectually deflroys this infection in all fubflances which can be for fome time expofed to it. Vide Lind's Obfervations on the Jail Difiemper, Ann. 1779 C 26 ] purifying of fuch clothes, furniture, &c. as cannot be injured by this treatment. But, although the degree of heat requifite for the complete deflruction of contagion can only be ufed for one particular purpofe, heat and fire, judicioufly managed, may, in various ways tend to leffen the power, or to check the progrefs of this pernicious vapour: for as clofe- nefs and dampnefs are favourable to the production and fpreading of contagion, drying and rarefying the air, by counteracting thefe, mull, fo far at leafl, be proper antidotes. But, independent of thofe effects of heat, an open fire, efpecially where the fuel is burnt in a narrow flue, is of great benefit; for, by confuming a portion of the air, it caufes a more fenfible renewal of it, and, in fact, is one of the befl ventilators. In employing fire and heat, however, care mufl be taken not to increafe the heat in the apartments of the fick, as this would prove more hurtful to them, than the drying or renewing of the air could be advantageous. The degree of cold neceffary to deflroy contagion is probably, like the degree of heat, inconfiftent with life ; and, therefore, although we hear of con- tagion having been checked or fuppreffed by cold, there are few inflances, if any, of its being com- pletely deflroyed. Befides, as it is not in our power to employ cold at pleafure, the queflion refpecting its effect, of whatever importance it /nay be to the pathologifl, is of little confequence to the practical phyfician. That noxious vapours are hurtful only when con- centrated, and are harmlefs when diffufed, are facts or data univerfally admitted ; and it is upon this principle, that clothes, bedding, or other matters to which contagion adheres, are purified, or lofe their deleterious qualify, by expofure for a fufficient length [ *7 ] length of time to the open air, or to a current of water; but, as the time requifite for this mode of purification is uncertain, and as contagious clothes, goods, &c. cannot always be expofed in a proper manner,* we are commonly under the neceffity of having recourfe to thofe more expeditious means of purification which chemiflry affords, and which I fhall next examine. The chemical means hitherto employed for de- flroying contagion, are the following : Burning fulphur with charcoal. -------with arfenic. nitre. gunpowder. portfire. tar. tobacco. wood. Boiling vinegar. -------with camphire. tar. Wafhing with vinegar. White-wafhing. Painting. The vapour produced by the burning of fulphur, is known to be the volatile vitriolic or fulphureous acid, one of the mofl powerful of the mineral kingdom, * Dr. Lind has very juflly remarked, that no ventilation or admiffion of air into prifons or hofpitals, can remove or deflroy contagion when once it is prefent. The fame may be faid of water. But though neither one nor the other un- der thofe circumftances can deftroy contagion, both may be ufefully employed in blunting its force, and in preventing the fpreading of the difeafe. [ *8 ] kingdom, the effect of which in deflroying conta- gion has been long cflablifhcd; but as it affecto, even in fmall quantity, the refpiration of animals, inducing fuffocation and death, it can only be em- ployed for fumigating clothes, furniture, or empty apartments. When burnt with charcoal, in the common way, we obtain not only the fulphurcous acid, but alfo the carbonic, or fixed air, which, though it can have little influence on contagion, renders the common air lefs fit for refpiration; a circumflance hardly deferving attention where the fulphur is burnt in a fumigating room, or a place fet apart exprefsly for the purpofe of fumigation, but which is of great importance when fulphur is burnt between the decks of ihips, or in hofpital or prifon wards, where men are foon afterwards to be lodged. The occafional addition of arfenic feems to have been made by Dr. Lind, with a view of increafing the deleterious* quality of the vapour; but it appears unneceffary, as the fulphureous acid is of itfelf fufficiently powerful for deflroying con- tagion ; befides, I doubt much, if the vapour of arfenic is not too heavy to rife with the acid of ful- phur. Burning or deflagrating nitre.— Having had fome experience of the efficacy of the nitrous acid in de- flroying contagion, and being fenfible of the difad- vantage of fumigating hofpital or prifon wards by burning fulphur with charcoal, as was commonly practifed, I refolved to employ nitre, inflead of ful- phur, at Winchefler; never doubting that I fhould obtain, * It was an old and very generally received opinion, that contagious di:eak>, as well as fome infeclions, were ciuled by inicvrs, and therefore Dr. Lind might think, that the molt deleterious vapour would prove the mod effectual in deltroying contagion. C *9 ] obtain, by deflagrating nitre, a portion of nitrous acid, as well as the dephlogiflicated nitrous air or oxygene ; but a farther acquaintance with chemiflry convinced me of my miflake, and that the deflagra- tion of nitre never produced any nitrous acid. It is therefore evident, that deflagrating nitre in the prifon and hofpital wards at Winchefler, could have no effect in deflroying contagion, and no far- ther effect in purifying them, but fo far as it fur- nifhed a quantity of oxygene, or air much purer than the common air of the atmofphere. I obferve, in Dr. RuuVs publication On the yel- low fever of Philadelphia, that the phyficians of that city lately fell into the fame miflake that I formerly did, viz. deflagrating or burning nitre as a means of deflroying contagion. Burning gunpowder.—If there is no nitrous acid obtained by burning or deflagrating pure nitre, we cannot expect to procure any from burning gun- powder,* either wet or dryf. The charcoal in the compofition poffibly yields a fmall quantity of car- bonic acid, whilfl the fulphur, uniting chiefly with the alkaline bafis of the nitre, forms a hepar ful- phuris, as the wrater ufed in waffling a gun plainly fhews. Burning portfire.\—This compofition of fulphur, nitre, and charcoal, has likewife been employed § for deflroying contagion ; and as the fulphur in this is * Gunpowder confifls of feventy-five parts of pure nitre, fifteen and a half of charcoal, and nine and a half of fulphur. f Next to the fmoke of wood, for purifying a tainted air, I efteem that of gunpowder. This I often ufe, as being quite inoffenfive to the lungs, &c. Vid. Lind on Fevers and Infections, p. 51. \ Portfire is made of one half fulphur, one fourth nitre, and as much charcoal. § Vid. Chifholm on the Weft India Fever. C 3° ] is the predominant article, it will perhaps furnifh fome fulphureous acid, though I fliould apprehend not a fufficient quantity to be effectual in dcflroying contagion. Burning tar.*—The ufe of tar fecms natural enough to failors, who may be fuppofed partial to what they are conflantly accuflomed; but, if we examine the fubject with attention, it is evident "that the vapour arifing from tar, whether burnt or boiled, muft be a weak agent againfl contagion. The empyreumatic oil can be of no fervice but by oppofing one difagreeable fmell to another, whilfl the ligneous acid, at belt a weak one compared with the mineral acids, is in great meafure deflroy- ed by burning, and is fo diffufed in the vapour of boiling tar, as to prevent entirely any effect which this acid, in a more concentrated flate, might other- wife produce. Burning tobacco.—There is an ancient prejudice refpecting the antipeflilential quality of tobacco, founded, I believe, on a tradition which is entirely void of truth, that the plague never entered a tobac- co fhop. Dr. Lind however feems to have had a high opinion of it,f but upon what this was found- ed I cannot pretend to fay, as the fmoke of tobac- co, fo far as I can perceive, has no advantage over the fmoke of any other vegetable matter. Burning * By fmokeing this fhip (Revenge) well with the vapour of tar, the infe&ion had abated. Vid. Lind, p. 2. f When prifoners can be removed, the infection will mofl effectually be extinguifhed by their removal to another pri- fon, and, after thoroughly cleaning the infected one, to fu- migate with the fmoke of tobacco, &c. Vide Dr. Lind's Health of Seamen, p. 337—Dr. Lind had fo high an opinion of the power of tobacco, that he advifed the buying up all the damaged tobacco, to be employed for this particular purpofe. C 3' ] Burning wood.—The fmoke* of a wood fire was reckoned, by Dr. Lind, one of the mofl powerful means of deflroying contagion, and he gives feveral examples where it was fuccefsfully employed. I might perhaps remark that fome of thefe examples he had from perfons who were not fuch accurate obfervers as himfelf; I (hall not however call them in queflion, as I think the advantage fuppofed to be immediately derived from the fmoke of wood, may fairly be afcribed to other caufes. In the firfl place, the fmoke of wood confifls principally of foot, or of inflammable matter unconfumed, with fome carbonic acid, neither of which can have any effect on contagion ; whilfl the ligneous acid is in very fmall quantity, too fmall certainly to be of much fervice. But we know, that where there is fmoke there is heat, and that where there is much fmoke, in places where people are prefent, a free admiffion mull be given to the air ; two circumflances which have confiderable influence in weakening the viru- lence, and in preventing the fpreading of contagion. Boiling vinegar.—Vinegarf has, at all times, been confidered as the grand antidote to contagion, though * A judicious application of fire and fmoke, is the true means appropriated for the definition and utter extinction of the mofl malignant fources of difeafe. Again it hath been experimentally found, that the fmoke of a wood fire ferves not only to leiftn the force or violence of fuch poifons, but is alfo an excellent protection againfl their being con- veyed. Vide Lind's Papers on Fevers and Infection. Paper i. p%49- f The cafcarilla bark, when burning, gives a mofl agree- able fcent to the chambers of the fick, and fo is at leafl an excellent prefervative, and may prevent bad fmells from taking effect. The fleam of boiling camphorated vinegar is flill more powerful for this purpole. Vide Lind on Fevers and Infection, p. 51. C 3^ ] though I believe it to be one of the mofl trifling means that has ever yet been employed. I have never once obferved the fmallefl benefit from its ufe ; and have known many fatal examples of con- tagion having been communicated where it was con- flantly employed. But although the fleam of boil- ing vinegar can be of no advantage in deflroying contagion, yet, as the fmell of it is grateful to the fick, it may for that reafon be ufed about their per- fons ; and. when camphire is diffolved in it, the fmell is flill more agreeable and reviving. Wafhing the furniture, floors, walls, &c. with vinegar, I confider as little better than wafhing them with fimple water. The fame may be faid of white-wafhing, as the lime and fize can have no particular effect. Oil painting, another mode of purifying apartments, has little advantage over the preceding ; not to mention the expcnfe and incon- venience attending it. But enough has been faid to fliew the general want of chemical knowledge, apparent in all the methods hitherto propofed for deitroying contagion, and more efpecially, the inefficacy of the methods employed in places and fituations from which peo- ple could not be removed ; I fhall now proceed to a more agreeable talk, and.explain thofe improve- ments, which a more accurate chemiflry, and a long attention to the fubject, have fuggefled to me, and relate fome experiments which 1 made, with a view to afcertain the efficacy of the nitrous acid, and the fafety with which it may be ufed, where people are neceffarily prefent. The mineral acids, particularly when in a flate of vapour, with the different gafes or permanently elaflic fluids produced by them, are probably, ex- cepting fire, the mofl powerful agents in nature, and C 33 ] and the fource of an infinite number of the differ- ent forms of matter obfervable in the mineral king- dom, and which are conflantly undergoing frefh changes, from their various combinations, and de- compofitions. But their power is not confined to the mineral kingdom ; they are known to have great influence likewife over putrefaction, and thofe other fpontaneous changes which vegetable and animal matter, deprived of life, undergoes ; and therefore, if the jail contagion, as I have endea- voured to prove, is a vapour produced by putre- faction, there cannot be a doubt that the mineral acids will prove effectual in deflroying it. So far we may reafon a priori; but let us next confult ex- perience, a lefs fallible guide. From this it ap- pears, that the volatile vitriolic or fulphureous acid, the only one hitherto made ufe of, proves effectual in deflroying contagion ; although owing to its de- leterious quality, it cannot be employed, except in fituations from which people can be removed. But, are the other mineral acids in a flate of va- pour equally dangerous «vith the fulphureous ? and, are they equally effectual in deflroying contagion ? To the firfl of thefe queflions I can give a pofitive anfwer ; to the fecond I can give one that, at leafl, is highly probable. In the firfl place, I can fafely affirm, that the nitrous acid may be employed in very great quanti- ty without riik, and even without the fmalleft in- convenience ; and, that it is effectual for the de- flroying of contagion, I have every reafon to be- lieve, not only from analogy, but from experience. I had frequently ufed the nitrous acid, as a fumiga- tion, in hofpital wards, and in the private apart- ments of the fick, without perceiving any unplea- fant effect from it; but, to afcertain with more E precifion C 34 ] precifion a fact of this importance, I made the fol- lowing experiments; in the conducting of which, Mr. Hume of Long-acre, a very ingenious man, and an excellent chemifl, was fo oblicrimr as to fa- vour me with his affillancc. We put a moufe, confined in a wire trap, under a glals cylindrical jar, capable of holding about 25 pints beer meafure, or 881 cubic inches; the jar was inverted upon wet fand, contained in a flat earthen trough or pan ; it was then filled with the fumes of the fmoking nitrous acid, introduced by means of a crooked glafs tube, until the animal could not be very diflinctly perceived. The moufe was kept in this fituation for a quarter of an hour, when the jar was removed, and the animal expofed to the open air; it immediately ran about the wire trap, as ufual, and had not the appearance of hav- ing fuffered the flightefl inconvenience from its con- finement. After a few minutes, the moufe was again put under the glafs jar, which was now filled with the vapour of pure nitrous acid, detached from nitre by the vitriolic acid. It remained much about the fame time as before, ana" when the jar was re- moved, feemed perfectly well. We repeated the fame experiments with a green- finch, only with fome little variation in the manner. We placed, on a table covered with green baize, a brown earthen veffel or pan, containing heated fand; in this was put a glafs faucer, with about: half an ounce of flrong vitriolic acid ; above which we placed the bird-cage, fupported with fome finali pieces of wood laid acrofs the pan ; then, add- ing a drachm or two of nitre, in powder, to the vitriolic acid, we covered the whole with the glafs jar. The nitrous acid rofe in fuch quantity, that in a very little time, the bird feemed as if in a cloud C 35 1 cloud or fo^. We kept it in this fituation fifteen minutes, by which time the cloud had difappeared, and the acid was in part condcnfed on the fide of the glafs jar ; during the whole time the bird nei- ther panted, nor appeared to fuffer any uneafinefs, from the atmofphere in which it was confined. We made trial alfo of the marine acid, by adding common fait, inflead of nitre, to heated vitriolic acid : during this experiment, the bird appeared to be, now and then, fomewhat uncafy, and opened its bill; but at the end of fifteen minutes, upon removing the jar, it hopped about as lively as be- fore. We then expofed the bird to the fumes of fulphur, burnt with an eighth part of nitre ; it im- mediately gave figns of uneafinefs, opened its bill,, and feemed to pant for breath in fuch a manner, that we were afraid to cover it with the glafs jar. We likewife made trial, in the open air, of the ox- ygenated marine acid :* for, as this is fo extremely deleterious, we did not think it fafe to expofe our- felves to the vapour of it in a room, nor did we venture to expofe the bird to it in any other way but in the open air, and even there it appeared to fuffer very much. Having made trial of the effect of the different mineral acids, in a flate of vapour, upon animals, we determined to render the experiment flill more conclufive, by trying what effect they would have on ourfelves. With this intention, we filled me room * The oxygenated marine acid is a difcovery of the famous Scheele, and has been recommended by Berthollet md Chaptal, two French chemifls, for the purpofe of ble iching. I am informed that it has alfo been lately ufed in France to deflroy contagion, but the particular circumflance,, and manner of its application, I have not yet learnt. C 36 ] room* in which we were with the fumes of nitrous acid, (obtained by mixing nitre with heated vitrio- lic acid, in the manner already defcribed) until the different objects became fomewhat obfeure, by a kind of fog or mill produced. The fire irons and fleel fender, loft their polifli, and the vapour arif- ing from a bottle of aqua ammonia; pura^, placed at fome diflance from the table, was evidently neutralized, as it iflued from the bottle, by the vapour of the nitrous acid. Air. Hume and I remained in the room the whole t':ne, without perceiving the flighteft inconveni- ence ; the fumes did not excite coughing, nor affect the eyes, in the way the fmoke of wood commonly does, even when I held my head over the glafs fau- ccr, and breathed them immediately arifing from it. We made trial likewife of the effect of the marine acid, w hich we found more pungent and ftimulating than the nitrous ; but, though it cx- cited coughing, it did not caufe that conflriction of the windpipe, and tightnefs at the chefl, with the fciiie of fuffocation, which is immediately induced by the volatile vitriolic or fulphureous acid. In- deed we were imprudent enough to try how far we could breathe this lafl, but I was inflantly obliged to run to the window for air, from the fenfe of conflriction, and of fuffocation, which it occafion- ed. W7e likewife tried the effect of the mixed fumes of the marine and nitrous acid, a kind of volatile aqua regia, which we found more pungent than the marine acid by itfelf. As for the oxygen- ated marine acid, perceiving the effect of it on the bird, * The room in which we ma do the experiments was a fmall parlour 13 feet by 10, and 8 feet high ; or about 1040 cubic feet. [ 37 ] bird, and knowing how extremely dangerous it is we did not venture to go very near it. From the preceding experiments, the different acid vapours, in refpect to the fafety with which they may be breathed, may be arranged in the following order : * ift. The vapour of nitrous acid, arifing from nitre decompofed by vitriolic acid. 2. Ditto—of nitrous acid in its fuming flate, or when the nitric acid is mixed with nitrous gas. 3. Ditto—of marine acid, arifing from common fait, decompofed by vitriolic acid. 4. Ditto—of nitrous and marine acids, obtained from the decompofition of nitre and com- mon fait by vitriolic acid. 5. Ditto—of fulphur, burnt with an eighth part of nitre. 6. Ditto—of fulphur, burnt with charcoal. 7. Ditto—of oxygenated marine acid,* obtained by putting manganefe to marine acid. As the firfl vapour is perfectly harmlefs, in any quantity in which it may be required, it is evident- ly the mofl proper to be employed in all fituations where people are neceffarily prefent; and if it fliould prove efficacious in deflroying contagion, of which I have not the fmallefl doubt, it is the defi- deratum,\ fo much fought after by Dr. Lind ; but which * The oxygenated marine acid is obtained, by diftilling marine acid from manganefe, but may alfo be procured in fmall quantity, by putting manganefe to heated marine acid, or by gradually adding a mixture of manganefe and fea-falt to heated vitriolic acid. f A certain method therefore of deflroying infection in places from whence perfons cannot be removed, is a defider- atum not yet obtained in phyfic. I have propofcd and tried C 38 ] which he confefTcs, with his ufual candour, he never could find out. The fecond, though more pungent than the firfl, may I believe be employed with the greateft fafcty ; at leafl, I have never obfei ved any inconvenience from ufmg it. But, as it cannot fo eafily be pro- cured in confiderable quantity, and is attended with greater inconvenience and expenfe, I have of late years only made ufe of the firfl. Our experiments likewife warrant us to affirm, that the third, or marine acid, though more flimu- lating, and more apt to excite coughing, than the nitrous, may be fafely ufed, at leafl in a moderate quantity, where people are prefent; and where ni- tre cannot be had, I fliould have no hefitation in employing it. Of the fourth I can fay but little, only that, in breathing it, I perceived it more pungent than the pure marine acid; and therefore, unlefs it fhould be found to poffefs fuperior efficacy in deflroying contagion, I would not employ it where there are people prefent. As the fifth never can be ufed with fafety where there are people prefent, its ufe mufl be folely con- fined to fumigating empty apartments, clothes, fur- niture, &c. The fixth fliould never be employed, as the car- bonic acid may do harm, and never can have any effect on contagion. Of the feventh I have no particular knowledge, only that it is extremely deleterious, and I believe extremely powerful; but whether it has more effeft on many things for this purpofe without fuccefs. Vide Lind's Obfervations on the Jail Diftemper. Edit, publifhed in Oct. '779- [ 39 ] on contagion than the other mineral acids, experi- ence only can determine. Having now fully proved that the nitrous, and poffibly alfo the marine acid, obtained in the man- ner already defcribed, may be employed with per- fect fafcty in hofpital and prifon wards, whilfl the people remain in them, I fhall, in the next place, relate how far my experience goes to afcertain the efficacy of thofe acids in deflroying contagion. From all the information I can procure, I do not find that any perfon has ever made ufe of the ni- trous acid to deflroy contagion but myfelf; for, as this acid is not produced by the deflagration of ni- tre, or of gunpowder, the employment of thefe cannot be confidered as an inflance to the contrary. I formerly mentioned, that I had employed the ni- trous acid in two different forms; either the va- pour arifing from the yellow or fmoking nitrous acid, which is a mixture of the acid with nitrous gas, or the more pure niffcous acid, detached from nitre, decompofed by the vitriolic acid. In one or other of thofe forms I have ufed it, both in hofpitals and in private practice, for fixteen or feventeen years pafi; and have had the fatisfadtion to obtain the mofl decifive evidence of its happy effect, in pre- venting the fpreading, or farther communication of contagion. The mofl highly contagious fevers that occur in our hofpitals, do not affect the patients in general lodged in the fame ward, but only the nurfes, or thofe patients who affifl them, or thofe who lie in the beds contiguous to the fick; to fuch perfons I have frequently feen the fever communicated, and have alfo repeatedly prevented the farther fpreading of the difeafe, by placing gallipots, with the fum- ing nitrous acid, between the beds of the fick and. C 40 ] of thofe who -were not yet affected by the conta- j gion. And, in private practice, I can declare with truth, that where the nitrous acid has been con- flantly ufed as a fumigation, I have not known an inllance of a contagious fever having been commu- nicated, even to a nurfe or an attendant. Thefe facts will, undoubtedly, be allowed to be very flrong evidence, with refpect to the power of the nitrous acid to deflroy contagion ; flill, howev- er, they are liable to fome uncertainty, and I will freely confefs, that the effect of the nitrous acid, fbr this purpofe, cannot be faid to be fully proved, until it has been tried in fumigating tainted clothes, 1 Sec. and until its power has been found fufficient to deflroy contagion on board of fhips, and in prifons and hofpitals, where it exifls in a much higher de- I gree than I have had occafion to fee it, excepting at Winchefler. It will probably be afked, why I did not make a complete trial of it there ? To this I anfwer, that with refpect to fumigating infected clothes, bed- ding, &c. I did not think myfelf warranted, efpe- cially on an occafion of fo much importance, to make trial of an uncertain remedy, when a certain one was in my power. As to fumigating the prifon and hofpital wards, it was evidently my intention to have employed the nitrous acid, but I was mif- taken in the means I took to procure it, and have not fince had a proper opportunity of repeating the experiment. The effect of the marine acid, in a flate of va- pour, on contagion, I have not yet had occafion to try, but have no doubt that it will be found of fuf- ficient efficacy for deflroying it; and, from the foregoing experiments, it is evident that, though not fo mild or fafe as the nitrous acid, it may be i.fcd, C 4> ] ufed, in a moderate quantity, even where people are prefent. The only purpofe to which 1 have ap- plied it, has been, when properly diluted, to wafh the hammock poflsj bedfleads, and furniture; alfo the floors, and Walls, of the apartments of the fick :* and I am perfuaded that, even in this way, it was extremely ferviceable, certainly more powerful than the mofl concentrated vinegar. I fhall now conclude this fubject with a few prac- tical rules or obfervations, which may be looked upon as corollaries, or inductions, from the pre- ceding experiments. The well known efficacy of the fulphureous acid, in deflroying contagion, is a fufficient reafon for our continuing to ufe it as a fumigation for clothes, furniture, &c. The nitrous acid, being attended with no rifle or inconvenience to the refpiration, and appearing, from our experience, of fufficient efficacy to prevent the farther fpreading of contagion, feems the proper antidote to be applied, in all fituations where per- fons are neceffarily prefent, and is, in fliort, the de- fideratum fought after by the benevolent Dr. Lind. For purifying empty hofpital or prifon wards, and fhips, I fhould alfo prefer the nitrous acid to the fulphureous; as I believe it to be equally effi- cacious ; its vapour is more volatile and penetra- ting ; and it does not leave the difagreeable fmell which fulphur does. But, for this particular ob- ject, I think it would be advifeable to make trial J F alfo * The wafhing the hammock pofis, walls, and floors of the prifon wards with the diluted marine acid, and the re- moval of all clothes, bedding, &c. proved completely effec- tual for deflroying the contagion at Wincheller ; as it is notf apparent, that the burning or deflagrating of nitre could con- tribute nothing to the fuoccf*. C 42 j alfo of the marine acid, and of the mixture of ni- trous and marine acids, as I am convinced of the efficacy of all the mineral acids for deflroying conta- gion, and our experience is not yet fufficient to de- termine their relative advantages, and difadvantages. To obtain the nitrous, or marine acid, in a flate of vapour, the method is extremely fimple. It con- fifls in decompofmg nitre, or common fait, by means of heated vitriolic acid, which may be done as follows: Put half an ounce* of vitriolic acid into a cruci- ble, or into a glafs or china cup, or deep faueer; warm this over a lamp, or in heated fand, adding to it from time to time fome nitre or common fait: thefe vcffels fhould be placed at twenty or thirty feet diflance from each other, according to the height of the cieling, or virulence of the contagion. In hofpitals, or prifons, the lamps, or veffels con- taining heated fand, may be placed on the floor; on board of fliips, it will be better to hang them to the cieling by waxed filk cords. The fumigating lamps, which I have feen at Moyfer's, in Greek- ftreet, Sol.o, a great number of which I was told have been fold to the navy, may be employed for this purpofe; although they would anfwer much better, if the faueer was deeper, and if, inftead of a place for a lamp, there was a box proper for con- taining hot fand, in which the faueer might be placed. As fumigating with nitrous acid is attended with no inconvenience, and as the procefs is fo fimple, and * As the quantity of vapour depends, in fome meafure, on the furfacc, 1 think it better to have the vitriolic acid put in a number of nnail vcffels, than in one or two large ones ; befides, in this v»ay, it has the advantage of bui." diffufed mo;; readily in any H\c:i fpj.ee. [ 43 ] and the materials fo cheap, it fliould, as a means of prevention, be employed for fome hours every day in tranfports having troops on board, and in crouded hofpitals; and, if there is any appearance of contagion, the fumigation fhould be executed with more care and attention, and the vapour con- fined for feveral hours at a time. Fumigating vef- fels, or lamps, fhould alfo be placed contiguous to the hammocks, or beds, of perfons affected with any contagious or putrid diflemper, whether fever or dyfentery. By taking fuch precautions, a great deal of mif- chief would probably be prevented, and a flop put, in the beginning, to one of the mofl fatal calami- ties* that ever afflicted mankind. * The late dreadful mortality in the Weft-India iflands, occafioned by a contagious fever imported from Boulam, has made too deep an impreflion on the minds of the people of this country to be foon forgotten, and every exertion on the part of the executive government will no doubt be made to prevent a repetition of the fame tragedy. $INCE [ 44 ] k5lNCE writing th- above, I have had the pica- fure of feeing the l.iit publication, and, as I ima- gine, the 1 ueft improvements, of the French che- mifts and phyficians on the fubject of contagion, and on the proper means of deflroying it. It is in- titled, " Instruction, fur les moyens d'entretenir la " fa'v.bnie, et de purifier PAir des Salles, dans les " Hcpiiaux ir.Hitaires de la Republique, fait au Con- " fed de Sante h 5 Ventofe, I'An 2d de la Rcpub- " liquc Francm[c une et indiviftble." This i.':sff uilihii, or ?ncn.oire, is divided into three parts. The firft relates folely to the means of cleanlinefs; the lecond to what are called the me- chanical means; and the third to the chemical. The two firft parts contain nothing new or intereft- ing; the third is of the greatefl importance to me- dical fcience, and particularly (0 to me, as it fur- nilhes a proof of the accuracy of fome of the pre- ceding experiments, and is a complete confirmation of the opinions I have long entertained reflecting the nature of contagion, and the power of the mineral acids to deflroy it. The French phyficians, inftructed by that excel- lent chemift Le Citoyen Guiton, better known by the name of Monf. de Morveau, of Dijon, have lately made trial of the marine acid in their hofpi- tals, and have found it equally effectual in deflroy- ing contagion as the fulphureous, and, as being more volatile, perhaps even preferable for the pur- pofe of purifying hofpital wards. They alfo re- marked that, in a fmallcr proportion, it may be fafely ufed in hofpital wards, even when people arc prdlnt.' The French phyficians however have r.ot * My cxpci.nv.:.'.. fhewcj the fame dfn^. Z 45 ] not employed the nitrous acid, nor made any trials of its effect on contagion; neither do they appear to have fufpected that the power of deflroying con* tagion was a quality inherent in all mineral acids; and probably, to a certain degree, in all acids, un- der certain circumllances. Although their experi- ence of the effect of the marine acid, together with my obfervations on that of the nitrous, feems to eftablifh the fact beyond the cavil of fcepticifm it- felf. Their method of obtaining the marine acid is the fame that I took to procure the nitrous; they either employed the fuming marine acid, or the acid detached from its alkaline bafis by vitriolic acid, ufing a confiderable degree of heat for that purpofe.* They likewife, upon the fuggeftion of M. Fourcroy, recommend adding a fmall quantity of the oxygenated marine acid; but, as they do not pretend to fay that they have had any experi- ence of the fuperior efficacy of this, and as the common marine acid has been found to anfwer the purpofe, I do not fee any reafon for making fo ha- zardous an addition. Another chemical procefs for purifying foul air in hofpitals, recommended in this instruclion, de- fences our notice. It confifts in placing, at dif- ferent diftances in the hofpital wards, veffels with lime water, for the purpofe of abforbing carbonic acid or fixed air. I am inclined, however, to be- lieve, that this advice is more the refult of chemi- cal theory than of practical obfervation; for I do not fuppofe that carbonic acid is ever prefent, (where there is a free admittance of air,) in fuffi- cient * The reader v.ill find at the end an account of their, procefs. [ 46 ] cient quantity to prove hurtful; at leafl, it can only affect the breathing, and has nothing in com- mon with contagious vapour. The French phyficians appear to me to have fal- len into a confiderable miflake on this fubject, in taking the quantity of carbonic acid prefent,* in an hofpital, as a teft of the quantity or malignity of contagion, when, in reality, they are two things totally diftinct from each other. The firft, or car- bonic acid, is a couftituent part of the common or atmofpheric air, which is greatly increafed by the refpiration of animals, and by burning candles, lamps, &c. and, when in too great quantity, ex- tinguifhes flame, and animal life : the other has no relation with the compofition of the atmofphere, never affects refpiration, but is produced by putri- dity, and excites fever. * The method propofed by the French phyficians, for afcertaining the quantity of carbonic acid prefent, is fimple and ingenious. Take two phials; let one be filled with common water, the other with lime water. At the place where you want to try the purity of the air, empty the phial of common water, then, filling it half full with lime-water, and corking it, fhake the phial for fome time : the quantity of fediment fhews the proportion of carbonic acid. But, to render the preceding experiment conclufive, the height from the ground at which the air is taken fliould be flated, otherwife we are liable to great fallacy. Extract \ [ 47 ] Extract from the " Instruclion, fur les Moyens " d'entretenir lafalubrite, et de purifier I'Air des " Salles dans les Hopitaux Militaires de la Repub- " lique, h?c. &c. &c" " Au nombrcs des moyens que la chimie a employes " avec un fucces que tient du prodige pour operer " cette depuration, nous citerons le procede que " Guiton, (Monf. de Morveau) reprefentant du " peuple, amis en ufage en 1773, dans la ci-devant " cathedrale de Dijon, infeclee par des exhumations, " au point qu'onfut oblige de Vabandonner. " Cr f» ^ vcrfi. dam le " »w»«f/