M. Faraday on Fumigation. 93 



supplying the disinfecting agent to the atmosphere of the place for 

 a length of time, would enable it better to act on the bedding, 

 clothing, and other articles left in the cells, and allow it also more 

 perfectly to penetrate to every part of the. building itself. 



The materials used were those generally employed, namely, com- 

 mon salt, oxide of manganese in powder, and oil of vitriol. Upon 

 making experiments with these substances as furnished by the dealer 

 for the fumigation, I found that a mixture of one part by weight 

 of common salt and one part of the oxide of manganese, when acted 

 upon by two parts of oil of vitriol previously mixed with one part 

 (by weight) of water, and Lft till cold, produced the best results. 

 Such a mixture made at temperatures of 60° Fahr. liberated no 

 muriatic acid ; but in a few minutes began to evolve chlorine, and 

 continued to do so for four days. When examined on the fifth 

 day, and urged by heat, so as to cause the liberation of all the 

 chlorine that could be afforded by it, only a small proportion was 

 obtained. Such a mixture may therefore be considered as having 

 libeTated its chlorine gradually but perfectly, without the applica- 

 tion of any extraneous heat ; and is therefore very proper for exten- 

 sive fumigation. 



The vessels in which the mixture is to be made should be flat, 

 and such as, being economical, are least acted on by the chlorine 

 or acid. Common red pans were used in the Penitentiary ; for 

 many being required at once, better earthen ware would have 

 been too expensive. They held each about four quarts. 



Preparatory to the fumigaJ;ion a quantity of the salt was turned 

 out, the lumps broken down by a mallet until the whole was in 

 powder, and then an equal wdight of the oxide of manganese 

 added, and the whole well mixed. The acid and water 

 were mixed in a wooden tub, the water being put in first, 

 thi-n about half the acid added, stirring at the same time. 

 When the heat produced had been dissipated, which happened iu 

 a few hours, the rest of the acid was added, stirring as before, and 

 the whole left till cold. The men used measures in mixing the 

 acid and water, and were told to take rather less of water than of 

 acid, 9 measures to 10 being nearly the quantities required. Any 



