FUMIGATION. 



FUNCTION, ARBITRARY. 



her generally, or particular parts. The vapour* of lint vincgnr, burn 

 ing sulphur, and of aromatic vegetable matter*, have been lung used t 

 counteract unpleasant or unwholesome amells : thi* u effected chieii \ 

 by the formation of such a* are stronger. The m.wt important kin-. 

 of fumigation U that which consists in the employment of HUC)I vapours 

 or gaaei at do not merely destroy unhealthy odours by exciting Biich 

 aa are more powerful, but which by their chemical action convert 

 dangerous miaimata into innocuous mutter. 



The fumigation of the first kind, that whieli is intended to produce 

 a healing effect, in now much leu employed than formerly; still, how- 

 ever, the bisulphide of mercury is occasionally used in vapour, <u 

 what U termed a mercurial fumigation, in certain forma of Kyplu!: -. 

 The use of vinegar, of aromatic pastilles, and even the smoke ot burn- 

 ing brown paper, which constitute the second kind of fumigation, il... - 

 not require any particular notice; their operation can hardly be 

 regarded as any other than that of substituting one smell for another. 

 In the last kind of fumigation three substances have been chiefly 

 employed, and in the gaseous state : first the vapour of burning 

 sulphur, or sulphurous acid gas, hydrochloric acid gas, nitrous acid 

 gas, and chlorine gas ; all but the last of these, or at any rate the 

 first and second named, appear to have been first used and recom- 

 mended by Dr. James Johnstone, of Worcester, about the year 1758 ; 

 in 1773 Ouyton de Morveau also mentioned the application of hydro- 

 chloric and nitrous acid gases, and in 1802 their use was still further 

 extended by Dr. J. C. Smith, who received a public remuneration as 

 the discoverer, which ho certainly was not. 



Chlorine gas, which is undoubtedly preferable to any disinfectant, 

 was first recommended by Dr. Hullo, who published a work on diabetes 

 in 1 797 ; he liberated the gas by the usual method of mixing sulphuric 

 acid, biuoxide of manganese, and common salt. When it is desirable 

 to produce a great effect in a short time, this is still unquestionably 

 the best mode of proceeding. 



We shall give an abstract of the mode adopted by Mr. Faraday in 

 fumigating the Penitentiary at Milbauk in 1825. (' Quarterly Journal/ 

 vol. xviii., p. 92.) 



The space requiring fumigation amounted to nearly 2,000,000 cubic 

 feet; and the surface of the walls, floors, ceilings, &c., was about 

 1,200,000 square feet. This surface was principally stone and brick, 

 moat of which had been lime-washed. A quantity of salt reduced to 

 powder was mixed with an equal weight of binoxide of manganese, and 

 upon this mixture were poured two parts of sulphuric acid, previously 

 diluted with one part of water, and cold. The acid and water were 

 mixed in a wooden tub, the water being first put in, and it being more 

 convenient to measure than to weigh the water and acid, ten measures 

 of water and nine of acid were used ; half the acid was first used, and 

 when the mixture had cooled the remainder was added. 



Into common red earthen pans, each capable of holding about a 

 gallon, were put 3J Ibs. of the mixed salt and manganese, and there 

 was then added such a measure of the diluted acid as weighed 4 J Ibs. ; 

 the mixture was well stirred and then left to itself, and all apertures 

 were well stopped. The action did not commence immediately, so 

 that there was sufficient time for the operator to go from pan to pan 

 without inconvenience. On entering a gallery 150 feet in length, a 

 few minutes after the mixture had been made, the general il 

 of chlorine was sufficiently evident ; in half an hour it was often almost 

 impossible to enter, and frequently on looking along the gallery the 

 yellow tint of the atmosphere could easily be perceived. Up to the 

 fifth day the colour of the chlorine could generally be observed in the 

 building ; after the sixth day the pans were removed, though some- 

 times with difficulty, and the gallery thus fumigated had its windows 

 and doors thrown open. The charge contained in each pan wan 

 estimated to yield about 5} cubic feet of chlorine gas ; in fumigating 

 a space of 2,000,000 cubic feet, about 700 Ibs. of common salt and the 

 same of binoxide of manganese were employed : and it will appear by 

 a slight calculation, that about 1710 cubic feet of chlorine were 

 employed to disinfect this space. In common cases, Mr. I 

 conceives that about one-half to one-fourth of this quantity of chlorine 

 would be sufficient 



When any cause for fumigation is continually recurring, and in 

 one cans alm< t im]* n . pi il.ly BO, the chloriile of lime or soda, 

 and especially of the former, has been within a few years success- 

 fully employed by M. Labarraque ; the exact nature of these com- 

 pounds is still under discussion, but the chloride of lime is a substance 

 well known and extensively employed under the name of bleaching- 

 ]>owder. 



We shall relate a few ex|>crimcnts performed by M. Qualticr de 

 Claiibry, illustrative of the mode in which these substances produce 

 their effects. A solution of chloride of lime cx|wsod to the air for 

 about two months, ceased to act u|xin litmus, contained no chlorine, 

 but a precipitate was funned in it which consisted entirely of carbonate 

 of lime, without any admixture of chlorine; it was th< ; 

 that the carbonic acid of the atmosphere had decomposed the chloride 

 of lime, evolved the chlorine, and precipitated the lime. Tli.il tlii 

 was the case was proved by passing atmospheric air through a solution 

 of poUak, licforc it was made to traverse one of chloride of Urn*; in 

 this case the poUsh wp'ii.il.-d the e;o so that no chlorin 



was evolved from HJ.- .|MM f cldo.ideof lime, nor wa* any pre- 

 cipitate formed in it ; in fact no thaugo whatever occurred. That it 



was the carbonic acid which produced this effect, was further proved 

 by poising a current of thi* gas into a solution of chloride of lime ; by 

 this it lost iti blenchiir,' power, the whole of the chlorine was expelled, 

 and all the lime converted into carbonate. 



In order to show the manner iu which these compounds of chlorine 

 and lime, and of chlorine and soda, act on putrid miasmata floating in 

 the air, some further experiments were made in the following manner : 

 Air was passed through blood which had been left t<> : eight 



days; being then passed through a solution of the chloride ,.. 

 carbonate of lime was deposited, and the ah- was rendered in- 

 and completely purified. In a second similar rx|>eriiuent the tv 

 was passed through a saturated solution of potash before it ;u 

 at the solution of chloride of lime; the latter had then no cffeci 

 it, and the air retained its insupportable odour; this hap; 

 evidently because the carbonic acid, which would otherwise have 

 evolved chlorine to have acted upon the putrid matter, was absorbed 

 by the potash. Another experiment was made with air left for 

 twenty-four hours over putreacent blood; the portion of it which 

 was passed directly through the chloride was perfectly purified, bat 

 when previously freed from carbonic acid the chloride had no 

 upon it. 



These experiments sufficiently prove that the carbonic acid in the 

 air, arising froni the various sources of respiration, combustion, and 

 the decomposition of animal and vegetable matter, liberates the chlo- 

 rine from its combination with lime or soda; and as this action i- 

 clow, the chlorine, though scarcely susceptible of affecting the animal 

 economy, readily decomposes putrid miasmata. It is therefore true 

 fumigation by chlorine, only it is less violent than that effected by the 

 rapid evolution of the gas, and it continues for a longer time. 



It is to be observed that chloride of lime U used in solution, and i.- 

 obtaiued by dissolving one part of bleaching powder in about 10U tim> - 

 its weight of water, and allowing the solution to become clear. This 

 is to be exposed to infected air, or in rooms which have any unpleasant 

 odour, in fiat vessels, in order that a sufficient surface may be acted 

 upon. If it should be required, the operation may be quickened by 

 the addition of a little vinegar, or of muriatic acid largely dilute' 1. In 

 some cases, where the disagreeable smell is extremely strom 

 where it would be difficult to expose a solution to slow action, it may 

 be thrown into the place, or the powder may be used, the at: 

 which would be more gradual and effectual. Chloride of soda i 

 pared only iu solution ; the process is given in the last edition of the 

 ' London Pharmacopoeia : ' it is however less easily obtained than the 

 chloride of lime, is more expensive, and not in any respect preferable ; 

 the solution is then called liquor sod;e chlorinate. 



1 T NOTION, ARBITRARY. In the integration of |>artial dill. - 

 reutial equations, arbitrary functions are introduced, that is, fun 

 which may be of any form whatsoever. Thus, in the problem of the 

 vibrations of a thin column of air, which leads to an equation of the 

 form 



the complete solution of the equation is 



s = <t> (y + ax) + ty (y ax) 



when <(> and ^ stand for any functions whatever. The determination of 

 these arbitrary functions must depend upon the data of the problem. 

 Thus, if it were required so to determine <t> and i/< as that c should 

 become x wheny isx, and .r 3 when y is l.c : we have then to determine 

 the forms of <t> and ^ from the two equations 



<ve) = x 

 cu) = x? 



4 (jc + o-c) 

 <t> (Iu: + (W) 



Those two functional equations might bo solved without mueh 

 difficulty, and forms of $.r nnd <tuc found. Theoretically, the del 

 nation of the arbitrary functions, so as to satisfy given conditions, 

 resolves itself into the solution of functional equations. 



Hut when these questions were first considered, it w.n soon seen 



'ie problems from which they are deriv. 

 tana . Kor instance, when the problem |i that of finding the 



r in which a di-amb.uico travels along a thin column of air. th 

 preceding equation exists, where z represent* the amount < 

 sion or rarefaction which exists in the air at a distance ;/ from a lixcd 

 origin at the end of the time .,- from the beginning of the m 

 Now, in practice, there is no disturbance of the state of the air 

 beginning of the motion, except in one small part of 

 a sound excited at one end of a cylindrical tube). Suppose, t 

 ample, that by introduction of external air, a certain amount o 

 presaion, <, is generated at the first moment (x - 0) throughout the 



, of the tube which extends from y = to y = HI. When .< = 0, 

 r is^y + ^'/, and the conditions of th. , / + $y 



should !H! equal tor when i/ b 



'll i/ in ipv.iter than /. II. !'.,-. <>,/ + <{.// In'. 

 oontinuoui function ; BO that in this ,-imple prob' 



IH are insufficient to express a volution, unless .iisconti 



us can be admitted among ' < 'H of partial din". -i 



equations. 



