^■^S Expir'wteiits on 5ugar.'~M,i!tiiig, 



gum, in the proportion of 135 to 117. The rcGduary charcoal of the fujjar alfo exccedid 

 that of the gum by l-Jth; but this may in fome meafure be accounted for from the greater 

 <iuantity of ihc hydro-carbonate yielded by rf»c latter. As oxygene is now allowed to be 

 the univcrfal acidifying principle, and as the acid yielded in both inflances (viz. the pyro- 

 inucous} was exaflly of the fame kind, it may be reafonably inferred, that the fugar which 

 afforded the greatell quantity of acid contained hkewife the greatell proportion of oxygene ; 

 for it is probable that both the carbonic acid and the hydro-carbonate were formed fro.ni 

 the decompofition of the water by the carbone of thcfc fubflances, as neither was produced 

 in any quantity until near the end of the operation : the oxygene, therefore, contained in 

 the former fliould not be confidered as entering eflcntially into the compofitioii of either 

 the gum or fugar. 



It is well known that vegetable mucilages and farcula are fomehow converted into fugar 

 by malting : we conceived, therefore, that it would throw confidcrable light on this fubjecl, 

 to obferve with more attention than had hitherto been done, the particular changes ami 

 decompofitions which take place during this procefs : it was with this view that the follow- 

 ing experiments were made : 



December i, 1796. A quantity of barley, after being foaked in water for 2+ hours, was 

 put into a wine-glafs, and introduced into a jar containing common air, and inverted over 

 water : the temperature in this and the following experiments was preferved between 60 

 and 70 as nearly as podible. At the end of five days it began to grow, and on the 28tli 

 the greateft part had thrown out flioots at leaft half an inch in length. On January 7, 

 vegetation was dill going on, and the air in the jar had fomewhat diminiflied : the barky 

 being now withdrawn was found to be very fwcet, and nearly converted into tlie Hate of malt. 

 The air in tlie jar was found to confift of azotic and carbonic acid gas in the proportion 

 cf 20 to 6, the whole of the oxygene being either abforbed, or converted into carbonic acid. 



January 19, 1797. A quantity of barley, prcvioully fteeped in water for 48 hours, was 

 Introduced, as in the laft experiment, into a jar containing oxygene gas, and inverted over 

 water to which fulphuric acid had been added. At the end of three days it began to grow, 

 and this procefs went on to the 29th. The water had now rifen confiderably in the jar, 

 the gas having fullered a diminution of about one-third. The barley being withdrawn 

 fmclled completely of malt, and tailed fweet. The gas in the jar, on examination, was 

 found to confift of 64 parts carbonic acid, 32 azote, and 4 oxygene ; from which it would 

 appear that the air employed in this experiment had contained originally about 20 per cent, 

 of azotic gas. 



To be more certain of the nature of the change wliich the pure air undergoes in this pro- 

 cefs, the experiment was repeated as follows : 



January 23. A quantity of barley, foaked in water for two days, was introduced into a 

 jar containing 46 meafures of very pure oxygene gas, and inverted over mercury. At tlie 

 end of three days the barley bcg,in to grow, and this procefs continued for ten days, al-' 

 though very flowly : tlxe column of gas remained exaclly of the fame iieight, fo that it had 

 undergone no apparent diminution or incrcafc : the barley being withdrawn, the air in the 

 jar was examined, and found to confift of carbonic acid gas, miscd with only i-ycth of its 

 bulk of oxygene gas. The barley was partly converted into malt, the (juautity of oxygene 

 being iuluftidcnt to produce this cluinge upon the whole. 



Auo;htr 



