Expenmtnts on Sugar. — J//(/.'/.<;». oji) 



Another experiment with common air was made at the fame thne, and exatUy under 

 (imilar circumftances. In this cafe the barley did not begin to grow until the end of the 

 fourth day ; and at the end of ten days had made much lefs progrefs than that in the oxy- 

 gene gas. It was now withdrawn, and the air in the jav, which had increafed a little, ex- 

 amined ; when it was found to confift of carbonic acid and azotic gas, in the proportion of 

 one to two very nearly, mixed with a very fmall quantity of o.xygene gas. A little of the 

 barley tafted fvveet. 



Being now fatisfied that during the evolution of the faccharine principle from vegetable 

 mucilage, a quantity of oxygene was either abforbed or converted into carbonic acid, we 

 widied to know if this procefs could take place in any degree without the prefence of this 

 gas. 



In order to determine this point the following experiments were made: 

 January 20. A quantity of barley, foaked as in the former experiments, was introduced 

 into a jar filled with, and inverted over, mercury. At tlie expiration of 1 2 days a very con- 

 fidej-ablequantityof gas was produced, at leaft five or fix times the bulk of the barley, but 

 nothing like vegetation was perceivable. The gas, on examination, was found to confift.cf 

 carbonic acid, being entirely abforbed by lime-water. The barley had not the leaft fweet 

 tafte, nor did it appear to have undergone any fenfible change. 



On January 20th, another portion of the fame foaked barley was introduced into a 

 wine-glafs, and placed in a jar containing nitrous gas inverted over water. At the ex- 

 piration of ten days the gas had undergone a flight diminution, but there was not the 

 fmalleft appearance of vegetation. The barley being withdrawn and examined was found 

 to have undergone no apparent change. The gas contained about one-ninth of its bulk of 

 carbonic acid, the remainder being pure nitrous gas, as was manifeft from the diminution 

 it underwent when mixed with pure air. The nitrous gas which difappcared in this in- 

 ftance muft have been abforbed either by the barley or the water. The carbonic acid which- 

 was found mixed with it is accounted for by the lad experiment. 



Two other portions of foaked barley were introduced into jars, the one containing hy- 

 drogenous and the other azotic gas, and inverted over mercury. At the expiration of 

 12 or 14 days there was not the leaft appearance of vegetation in either, but the gas in both 

 had increafed in bulk about one-fifth. The barley being withdrawn and examined, that 

 in the hydrogenous gas tafted mufty, but not in the leaft fwect ; the portion in the azote 

 appeared to have undergone no change. The gas in both jars contained from one-third to 

 one-fourth of its bulk of carbonic acid, the remainder being the original gafesnot fenfibiy- 

 changed. 



From thefe experiments, therefore, it is manifeft that oxygene is abfolutely nece/Ttiry for 

 the converfion of vegetable mucilage into fugar ; as in no one inftance was faccharine mat- 

 ter formed where this was not prefent, and the quantity of the former was always iti proi 

 portion to tliat of the latter ; for we found in all the experiments, that wlicn the cvygefte 

 was confumcd this procefs immediately ceafed. i:I 



It may ftill remain doubtful, whether the oxygene is abforbed by the barley, or merely-' 

 converted into carbonic acid : we arc inclined to tliink that it is chicHy abforbed, altlifl(r{;hi 

 pArt may alfo be confumcd in the formation of this acid; for we Iiavc fifc<i that carbonic 

 acid is formed without the prefence of oxygene gas, and that irf very confidcrable quWrnityj ' 



X " 3 w\uc\v 



