VOL. LXXXIV.] PHILOSOPHICAL TRANSACTIONS, 425 



room in my house, it was capable of effecting a change in their electrical state, 

 excepting in those which were under ground ; for in the 2 kitchens, the open 

 area, and coal-vault, the doubler became electrified positively ; in the 1 former 

 rooms speedily, but in the 2 latter, that lay more to the sun, slowly. I have 

 observed before, that the air in the garret was infected with a noxious exhalation, 

 which I now judge came from the wearing apparel laid up in it : whereas the air 

 in the kitchens was not only much cooler, but perfectly clear of all offensive 

 exhalations. However, on July J 7, the 1 kitchens were white-washed and 

 painted, and of course were filled with a noxious effluvium. The day after I 

 worked the doubler in the kitchens, and by a very few turns of the revolving 

 plate it gave negative electricity. 



Knightsbridge charity-school occupies a piece of ground between the north 

 end of the chapel and Hyde-Park wall ; and the main sewer of that neighbour- 

 hood runs at no great depth under it ; the number of children educated in this 

 school is thought by some to be too great for the size of the school ; on these 

 accounts it becomes infected with a very disagreeable stench, especially when the 

 door and windows are shut up ; I have sometimes found the noxious effluvium so 

 very strong in this school, that I have hastened out to breathe a purer air. I 

 have often examined the electrical state of the air in this school with the doubler, 

 and have always found it strongly negative ; which showed that the aqueous or 

 other conducting matter lodged in the air of the school, possessed less than their 

 natural quantity of electricity ; while that of the school-master's parlour adjoin- 

 ing, having nobody in it, possessed somewhat more than its natural quantity, it 

 was found therefore positively electrified. 



July 5th, therm. 76°, I went to the school, and found the door and windows 

 set wide open to let in cool air ; I now perceived no stench at all in the school, 

 and thought it needless to try it. However the schoolmaster observed that the 

 further end of the school was at all times most infected with, and seldom quite 

 clear of stench. I therefore worked the doubler in that part of it, and after a 

 very few turns it became electrified negatively, rather against my expectation. I 

 then tried the other end of the school, which, by the door being wide open, was 

 less liable to retain any noxious effluvium, and there the doubler gave positive 

 electricity. After this I tried it in the schoolmaster's parlour, where it was posi- 

 tive also. Some other like experiments, with similar effects are here related ; 

 from which Mr. R. concludes, that, without even attempting to consider in this 

 place how far the influence of electricity is concerned in all sorts of vitiated air, 

 it will be sufficient to remark, as it clearly follows from the preceding experi- 

 ments, that air infected with animal respiration, or vegetable putrefaction, is 

 always electrified negatively, when at the same time the surrounding atmosphere 

 is electrified positively. 



VOL. XVII. 3 1 



