IMAGE EVALUATION TEST TARGET (MT-3) Cfo 1.0 I.I 25 2.2 us lAO I 2.0 m 1^ IIIIJ^ i^ < 6" ^ <^ »> aignifia "A SUIVRE", la aymbola ▼ aignifia "FIN". Mapa. plataa, charta. ate., may be filmed at different reduction ratioa. Thoaa too lerge to be entirely included in one expoeure are filmed beginning in the upper left hend comer, left to right and top to bottom, aa many framea aa required. The following diagrama illuatrata the method: Lee cartea. planchect. tableaux, etc.. peuvent ttre fUmAe A dee taux da rAduction diff Arents. Loraqua la document eet trop grend pour Atre reproduK en un aeul clichA. il eet filmA A partir da I'angia aupAriaur gauche, do gauche A droite, et do haut en bee. en prenent le nombre d'imegea nAcaeaaira. Lea diagrammee suivanta illuatrent la mAthode. 1 2 3 1 2 3 4 5 6 ^1'- Mri Beprlnted for the Autlior from the'BRinsn Hsoicii. Joubitai., December 25th, 1807. NOTES ON HOUSEHOLD DISINFECTION BT FORMALDEHYDE. Paper read in the Section of Pathology and Bactertohgu, at the Annual Meetiruf of the British Meaical Association held in Montreal, September, 1897. By Wtatt Johnston, M.D. BaoteriologlBt to the Board of Health of the Province of Quebec (in collaboration with D. D. MoTaggart, M.D.) DiTRiNO the past year the nae of formaldehyde as a disinfect* ant has been greatly increased in America, its efScaoy having largely become known throngh the work of Dr. J. J. Kinvonn and Professor F. 0. Robinson. It is astonishing how little we actually know of what actually happens in the ordinary roatine disinfection of rooms by diflTerent methods in com- parison with onr knowledge of what happens under more rigid experimental conditions. It seemed that devising simple and fairly uniform methods o" testing room disin- fection which would enable it to be done by the ordinary sanitary officials in the regular course of their duties, import- ant information oould be obtained which would be of service in making a choice of methods. I have designed a little outfit for use by the Board of Health of the Province of Quebec for this puri)ose, in which by having the infected test objects (small bits of rubber bands dipped in bouillon culture) placed in muslin i>ackets of distinctive colours, the degree of penetration of steam or disinfectant vapours can be tested by an unskilled person (a red packet is exposed near source of disinfectant, a yellow packet is exposed far from source of disinfectant, a green packet is covered lightly or placed in a pocket, a blue packet IS covered deeply in a blanket roll or in a mattress). The Sackets to go in an envelope marked with blank spaces for etails as to cubic space, amount of disinfectant used, etc.. and can be sent by post. The use of colours and a small metal fastening for the packets also enables any bleachinff or tarnishing effects to be detected. These were invariably g resent mth sulphur fumigation, never with formaldehyde, uring the past year, a good deal of disinfection of elegant private houses has been done by us. No injury whatever has been reported from formalin. In planning the test outfit, valuable advice was received from Dr. W. H. Park (New York). Practically these test outfits were found to V f m resnlt nnder with snlphnr not only the the cost of The methods answer well. Staphylococcus anrens was the test organism chiefly nsed. Spore cultures were only employed in case of steam. We found that, owing to the high inhibitory powers of even minute traces of formalin, it was best to neutralise the test objects in excess of ammonia before making cultures, or to allow several hours to elapse. The desiderata in room disinfection we would rank as follows : 1. Efficiency especially as to certainty of known conditions. The uncertainty of action gas is a great drawback. 2. Freedom from injury to the goods treated. 3. Cost, in which there must be included direct outlay for the disinfection itself, but apparatus, staff, means of transportation, etc. . in general use are disinfection by solutions and fumigation by sulphur or formalin, with steam for articles which require penetration. Preliminary fumigation, so as to disinfect the surfaces of articles to be removed for steam treatment is a safeguard, but causes delay. What I have to report at present con sems the use of formal- dehyde. As is well known, solutions of this substance are powerful and rapid disinfectants, and the vapour has shown considerable powers of penetration. If not so rapid in its action as steam, it is far more certain than sulphur gas, and has no tendency whatever to destroy goods. In room disinfection I have chiefly employed regenerators, by which the gas is liberated under pressure from a mixture 01 equal parts of formalin and 20 per cent, calcium chloride solution. The small apparatus made by the Sanitary Con- struction Company (New York) has been found on the whole most convenient, though I have tried a number of others. My experience with formaldehyde lamps has been less satis- factory. Their effects seemed uncertain, and a quantity of methyl alcohol vapour passes off unconverted as the draft of the lamp increases. The results as to penetration were relatively more satisfactory when the lamps were used in a small enclosed space than would be expected from the results obtained in ordinary rooms. y/e found that it was advisable to use larger quantities of formaldehyde than are generally advised, and our results, at first disappointing, became very satisfactory upon using i lb. of formaldehyde per 1,000 cubic feet 01 i quart wood alcohol for the same space, and prolonging the actual time of gener- ating the vapour to from one to three hours. We notice that others who, at first, recommended smaller amounts, now advise larger ones. Most of those who report poor results with formaldehyde use small amounts of the agent. Those wl\pse results are surprisingly good with minute quantities of disinfectant we find usually einploy culture methods, which do not exclude all inhibitory effects. The cost for private disinfection is not considbrable, at the rate of 2^ to 30 cents per lb. per 1,000 cubic feet, and though this would be relatively high in municipal work, it is not at all prohibitory. With these quantities, we succeeded in most instances in securing sterilisation of the exposed objects, and of a large proportion of these lightly covered, that is, placed in pockets or beneath the bed clothes or pillows, but in room fumigation, test objects placed inside blankets or inside matresses were not sterilised. We have to deal in the con* 3 tents of an ordinary Bick room with several diffevent sets of articles. First, surfaces cnrtains which are relatively acces- sible to vapours. Secondly, carpets and hangings, which are less accessible. Thirdly, blankets, mattresses, and pillows, which are difficult to penetrate. In order to disinfect articles of the second and third classes in an ordinary room, a great excess of vapour and consequent waste is necessary. By the use of closed chambers, a greater penetration of the vapour can be secured, and a smaller amount is required. The vacuum method of securing penetration does not appear to give the same rapidity of eaect that it does in the case of steam. We have been able to secure complete sterilisation in two hours of test objects placed in a closely rolled blanket, by using a vacuum of 15 inches followed by an air pressure of 10 lbs. In this apparatus, however, the steam jacket had to be incidentally heated in obtaining the vacuum, and the action of formaldehyde is known to be increased in proportion to the temperature. In any case, the use of a vacuum does not make penetration a matter of a few minutes as in the case of steam. Placing the articles in a cupboard or trunk, and blowing in the vapour usually gave fair penetration, if excess of vapour was used. Pasting up minute cracks does not appear to make much difference. Though no large crevices or draughts should be allowed in the room we found it quicker and less trouble- some to generate an excess of the vapour than to paste up cracks. I have devoted some attention to constructing a Sortable chamber or receptacle suitable for room disinfection, ne such chamber, 40 inches by 30 inches by 60 inches, made of galvanised sheet iron was light enough to be carried (witii some difficulty) on a stretcher by two men, and could be closed so as to give a vacuum of 2 to 3 inches. This was found clumsy in actual practice, and the saving in time did not permit of its being used in two places on the same day. Out of door disinfection is out of question in a Cpoiadian winter. Becently I have tried the plan of using a tent or canopy with those articles requiring most penetration placed beneath it, spread out on convenient articles of furniture. The gas being conducted under this by a rubber tube gave some increase of penetration, while enough escaped from beneaUi it to sterilise the exposed surfaces in the room. My latest attempt in this direction has been the con- stmction of bags which are as nearly as possible air tight or Ss tight. The cost does not exceed 5 to 8 dollars for one as rge as an ordinary disinfectant chamber, 5 ft. by 3 ft. by 4 ft. By using " enamelled duck " and having a projecting nap round the open end so as to be rolled up with a corresponding flap of the cover, the sealing up is fairly good, though capable of improvement in construction. Owing to an unexpected interruption to work, I have not yet had an opportunity of testing this apparatus thoroughly at the time of the meeting, but it appears worthy of trial to see whether the best results are got by blowing in the vapour and by placing in articles which have been sprayed with formalin solutions. Carpets, rugs, mattresses, and pillows can be well sprinkled without being drenched, and placed in the bag, or when the articles cannot stand direct wetting, clothes drenched with the solu- tion can be placed inside. In this way the effects of disin- fectant spraying are greatly enhanced, though to what precise extent this may prove useful in room disinfection I am not II at present able to say. From the first, I have been stronsly of opinion that methods which permitted of all the articles in the sick room being disinfected without the necessity of removal was very desirable for localities unprovided with larger disinfecting plants and staffs, and that even in cities, economy might be effected by thus doing away with trans- portation. With regard to disinfecting solations, my favourite one is formalin used by means of a pump or spray, as suggested by A. O. Abbott. A i to I percent, solution seems sumolent, and the cost of this, though more than than that of i-iooo sublimate, is only about two cents per gallon. The pump used costs a few shillings, and weighs but a few ounces, but apparently answers just as well as the heavy and expensive Equifez sprays sold for the purpose. The public need clearer ideas of the ** effective cost " of different disinfectant solu- tions—that is to say the cost of a given quantity of solution of effective strength. I think that the adoption of a uniform standard, say, that sufficient to destroy sta^ylococcus aureus in five minutes would be a convenient strength for house dis- infection. The effective cost of several disinfectants is about as follows, when used in amounts generally required for private disinfection: Oarbolic acid, 1-30, costs 7 cents per litre. Sublimate, i-iooo, costs \ cent per litre. Formaldehyde, 40 per cent, strength, 1-200, coats 1 cent per litre.^ Few realise the waste of money involved in the use of oarbolic acid. The cheaper grades sold as carbolic acid con- tain practically no phenol at all. Other things being equal, I think that preference should be* given to substances which are not poisonous. I need not here go into the matter of formalin vapour for treating goods liable to be injured by steam or disinfecting solutions further than to say that it is a most satisfactory agent for this work for which we previously had no reliable method. Whether the dust in the walls and cracks are absolutely sterilised or not by fumigation, most sanitarians will agree that the average fumigation suffices to remove the danger of infection from exposed surfaces, as far as can be judged from epidemiological evidence. NOTB. 1 Recent reports seem to show that the very oonservatlve estimate of the effective strength assigned to formaldehyde is too low. Thus Le Dento (iStem. M6d., 1807, p. 3x5) stated that instead of the 40 per cent, com- mercial solution being one-fifth as effective as the same weight of sublimate It is really twice as effective in equal quantities. This, if true, would raise the effective strength of formalin and formol to tenfold what Is represented in the table. \\ ■Hi