94 M. Faraday on Fumigation. 



slight departure from these proportions would be of no conse- 

 quence. The pans were then charged, each wiih about 3ilb. of 

 the mixed salt and manganese, and distributed at proper intervals 

 along the galleries, ^-c, care having been taken previously to close 

 the doors and windows, and to stop with mats or rugs all 

 apertures to which access could be had, especially key-holes, 

 through which there was any draft. The diluted acid being cold 

 was then carried in cans or jugs, and measured out in the propor- 

 tion of 4iL.lb. to each pan, the mixture being well stirred with a 

 stick, and left to itself. This was done without any inconve- 

 nience to the operator, except when the acid was applied too 

 warm : there was abundant time to go from pan to pan, and 

 to close the various galleries in succession. On entering a gallery 

 a few minutes after it had been thus treated, the general diffusion 

 of the chlorine in the atmosphere was sufficiently evident. In 

 half an hour it was often almost impossible to enter, and fre- 

 quently on looking along the gallery (150 feet in length), the 

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

 the fifth day the odour of the chlorine could generally be observed 

 in the building. After the sixth the pans were removed, 

 thou'^'h sometimes with difficulty, to be emptied and used else- 

 where ; and the place fumigated, had its windows and doors 

 thrown open. 



It was estimated that the charge of each pan would yield about 

 lib. of chlorine, or 63 cubical feet. The whole quantity of mate- 

 rials used was 7001b. of common salt, 7001b. oxide of man- 

 ganese, and 14001b. of oil of vitriol. The space requiring 

 fumio-ation amounted to nearly 2,000,000 cubical feet, and the 

 surface of the walls, floors, ceilings, §r., exclusive of fur- 

 niture, bedding, ^r., was about 1,200,000 square feet. This sur- 

 face was principally stone and brick, most of which had been 

 lime-washed. The space was divided into 72 galleries of 150 

 feet each in length, and towers, passages, chapel, S(C., equivalent 

 to about 13 galleries more. The number of cells, rooms, ^-c, was 

 nearly 1200. 



It was desirable for many reasons that the Penitentiary should 



