190 FUMIGATION METHODS 



cubic feet capacity, of which the horizontal dimensions 

 were 13^ feet by i^ feet and the vertical i}^ feet. 

 The experiments covered five different cases, and it 

 appears first that there is less uniformity than with 

 the box of 60 cubic feet. This may be due, and prob- 

 ably is in part, to the structure of the two boxes, the 

 former having rawhide roofing paper sides and the 

 latter double sides with paper lining. Hence in the 

 case of the box under discussion outside disturbing 

 influences may have been felt to a greater degree. 



' ' With the intake at the same end of the box as 

 the generator, after three minutes' diffusion time there 

 appeared in a single instance a deficit of acid vapor as 

 compared with the normal, in two other instances a 

 considerable excess. The extreme fluctuations found 

 show forcibly the inconstancy of spontaneous diffusion, 

 especially with this arrangement and after a short 

 interval of time. With the generator at the middle of 

 the box and the intake at the end there is greater uni- 

 formity and after ten minutes a considerable deficit, 

 which deficit remains practically the same for a half 

 hour ; the amount of vapor then gradually diminishes, 

 doubtless through leakage. It appears then that of 

 these two arrangements, viz., the generator in one 

 case at the end of the box and again in the middle, 

 the latter gives more uniform results and also a more 

 even distribution of the acid vapor. This is, perhaps, 

 what would be expected, but it must be noted that 

 even in the latter case the quantity of vapor in one 

 instance is double what it is in two other instances. 



"/ summary, then, be it noted of these cases of 

 spontaneous diffusion that within a half hour of diffu- 



