DIFFUSION OF HYDROCYANIC ACID VAPOR 193 



soil. Hence, in a box resting on soil, about 62 per 

 cent, as much acid vapor is available as in a closed 

 box. It would seem necessary, then, in work of this 

 sort over soil to use nearly twice as much cyanide and 

 other reagents as in a closed box." 



Diffusion in large room. " Bxperiments were made 

 in a rectangular room of which the horizontal dimen- 

 sions were 20 feet 9 inches by 19 feet i inch, and the 

 height 10 feet n inches, and which included 4,332 

 cubic feet. The walls and ceiling were plastered and 

 the floor was of boards ; there were four windows and 

 three doors. The crevices were stopped as far as 

 possible, but necessarily the room was far from air- 

 tight. Samples of air were taken simultaneously from 

 three different points within the room. The position 

 of two of these points and also of the generator was 

 changed several times in order to study the diffusion 

 in different places. The generator was a glazed stone- 

 ware vessel 8 inches in diameter and 1 5 inches high. 

 The charge of reagents in the case of the room-experi- 

 ments was the same per cubic foot as in the case of the 

 box-experiments, in the former amounting to 866.5 

 grammes cyanide, 1,300 c. c. of concentrated sulfuric 

 acid, and 1,950 c. c. of water. The water was poured 

 into the generator, the acid was then poured into the 

 water, and immediately thereafter the cyanide, wrap- 

 ped in paper, was dropped by means of a string, into 

 the acid mixture." 



General results. "After ten minutes of diffusion 

 time, with the generator in one corner on the floor, the 

 amount of vapor in the center of the room at the ceiling 



