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THE POPULAR SCIENCE MONTHLY 



room is fairly indicated by the following 

 statistics, the result of a large number of 

 observations made by Mr. Richard Weaver 

 in the schools and manufactories of Lei- 

 cester, England : As carbonic-acid gas is 

 usually the chief impurity in rebreathed air, 

 being produced in large quantities by both 

 breathing and combustion, Mr. Weaver 

 takes it as the measure of aerial contami- 

 nation, the amount present under ordinary 

 circumstances enabling us to judge of the 

 degree of vitiation caused by the other prod- 

 ucts of respiration and combustion. Set- 

 ting out with the established fact that free 

 or what is commonly called pure air con- 

 tains, for every thousand parts, very nearly 

 four-tenths of one part of carbonic acid, Mr. 

 Weaver found in the air of a room where 

 six persons worked at boot and shoe finish- 

 ing, each person having 51 cubic feet of 

 space, that the proportion of carbonic acid 

 was 5.28 parts per thousand, or more than 

 thirteen times as much as Nature, when let 

 alone, allows. In another instance, where 

 the air-space to each of fourteen individ- 

 uals was 186 cubic feet, with fourteen 

 gas-lights burning, the amount of carbonic 

 acid, to a thousand parts of air, was 5.32. 

 In a class-room of one of the national 

 schools, and the science class-room at that, 

 seventeen pupils, each with 200 cubic feet 

 of space, were breathing an atmosphere 

 containing 2.41 parts per thousand of car- 

 bonic acid, or six times as much as the air 

 contains in exposed situations. In no case 

 examined was the proportion of carbonic 

 acid as low as one part in a thousand of 

 air ; the average in fifteen places being 3.14 

 per thousand, or nearly eight times as much 

 as in pure air. It is hardly necessary to 

 add that the provisions for ventilation, 

 where any thing of the kind was attempted, 

 were of the most imperfect character. But 

 what may be effected by ventilation was 

 strikingly shown in the instance of a 

 boy's day-room in one of the national 

 schools, where there were one hundred 

 pupils, each with 236 cubic feet of air- 

 space. The ventilators were placed in the 

 roof, and, though very far from perfect, 

 the air in the room contained only 1.16 

 parts of carbonic acid to the thousand, 

 the lowest proportion observed in any of the 

 fifteen cases examined. Mr. Weaver states 



that the atmosphere in several of the rooms 

 was very offensive, and in every case a 

 pleasurable sense of relief was experienced 

 on entering the outer air. Large space, 

 without ventilation, he considers of little 

 avail, as it has no advantage over a small 

 room except that the air is a little longer in 

 attaining the same degree of contamination. 



Careless Disinfection. In cleansing and 

 disinfecting rooms that have been occu- 

 pied by persons sick with contagious dis- 

 eases, mere exposure to disenfecting va- 

 pors is not enough to thoroughly rid the 

 apartment of danger to future inmates. The 

 floors and wood-work require thorough 

 scouring with some disinfecting fluid, and 

 the walls and ceiling should also be careful- 

 ly cleaned. If the walls are covered with 

 paper, nothing short of its removal will be 

 effectual, as it unquestionably has the 

 power of absorbing and retaining contagious 

 matters, that are not reached by the ordi- 

 nary processes of disinfection. And its re- 

 moval is all the more necessary where sev- 

 eral thicknesses are plastered on the wall, 

 for then the deeper layers are quite beyond 

 any possibility of being cleansed ; and, apart 

 from the danger of contagion, the presence 

 of paste in such quantities, as several thick- 

 nesses of paper involve, liable in warm 

 weather to ferment and decompose, and at 

 all times furnishing a nest for hosts of vermin, 

 is certainly most objectionable. That wall- 

 paper does actually furnish lodgment for con- 

 tagion, and the paste with which it is stuck 

 on food for vermin, is proved by the following 

 cases reported in the Lancet: The work- 

 men engaged in stripping the paper from 

 the walls of a house in Manchester, that had 

 previously been occupied by persons ill with 

 fever, nearly all came down with the same 

 fever, although previous to their visit the 

 house had been disinfected with chlorine 

 and carbolic acid. In the Knightsbridge 

 barracks, where numerous layers of paper 

 and paste had been allowed to accumulate, 

 the walls when examined were found to be 

 literally swarming with maggots, that were 

 leading a most flourishing existence while 

 subsisting on the paste between the several 

 thicknesses of paper. The practice of fresh- 

 ening the walls of rooms by covering up, in- 

 stead of removing the filth, has become ex- 



