55 
The gas contained about l-Qth of its bulk of carbonic acid, the remainder 
being pure nitrous gas, as was manifest from the diminution it underwent 
when mixed with pure air. 
The nitrons gas which disappeared in this instance must have been ab¬ 
sorbed either by the barley or the water; the carbonic acid which was found 
mixed with it, is accounted for by the last experiment. 
EXPERIMENT VII. and VIII. 
Two other portions of soaked barley were introduced into jars, the one 
containing hydrogenous* and the other azotic gao, and these were inverted 
over mercury. 
At the expiration of 12 or 14 days there was not the least appearance 
of vegetation in either, but the gas in both had increased in bulk about 
1-oth. The barley being withdrawn and examined, that in the hydrogenous 
gas tasted musty, but not in the leaot 4weet\ the portion in the azote ap¬ 
peared to have undergone no change. 
The gas in both jars contained from l-3d to l-4th of its bulk of carbonic 
acid, the remainder being the original gases not sensibly changed. 
CONCLUSION from these EXPERIMENTS. 
From these experiments, therefore, it is manifest that oxygen is absolutely 
necessary for the conversion of vegetable mucilage into sugar, the food of 
the embryo; as in no one instance was saccharine matter formed where this 
was not present, and the quantity of the former was always in proportion to 
that of the latter; for we found in all our experiments, that when the oxygen 
was consumed this process immediately ceased, and that its quickness was 
in proportion to the oxygen present.T 
In the year l^SQ the late Dr. Ingenhousz made the following experi¬ 
ments, with a view to ascertain what opecieo, or mixture of air4, was moot 
favourable to the growth of oeedo. 
* For the nature and production of hydrogen gas see note * page 56. 
f The above-related experiments were made by my very ingenious friend Mr. Cruickshaxk, 
chemist to the Ordnance. 
