388 
PHYSIOLOGY. 
BOOK II. 
four hours on a mignonette plant. Twenty- three cubic inches, 
with five times their volume of air, appeared to have as little 
effect in the same time ; but the plant began to droop when it 
was removed from the jar, and could not be revived. 
Olefiant gas, in the quantity of four cubic inches and a 
half, and in the proportion of a hundredth part of the air, had 
no effect whatever in twenty-four hours. 
“ The protoxide of nitrogen, or intoxicating gas, the last we 
shall mention, is the least injurious of all those we have tried; 
indeed, it appears hardly to injure vegetation at all. Seventy- 
two cubic inches were placed with a mignonette plant, in a 
ar of the capacity of 500 cubic inches, for forty-eight hours ; 
but no perceptible change had taken place at the end of that 
time.” 
Gbppert has also found that hydrocyanic acid in a gaseous 
state is fatal to vegetation. Numerous experiments upon the 
action of this and other substances deadly to plants are 
to be found in this author’s dissertation, De Acidi Hydro- 
cyanici Vi in Plantas : Vratislav. 1827. 
