164 Dr. H. Karsten on the Theory 



carbonic acid for a time, passed into a state of alcoholic fer- 

 mentation, whilst they still appeared externally to be perfectly 

 sound and well-preserved. From twenty-four plums which 

 had lain for a few days in carbonic acid, and had almost im- 

 proved in apparent soundness and firmness of flesh, he obtained 

 Q'5 grms. of absolute alcohol. In this case also Pasteur de- 

 rives the alcoholic fermentation from the absence of oxygen. 



I also obtained an alcoholic distillate from grapes and plums 

 under similar circumstances, not only when they were pre- 

 served in carbonic acid, but also in hydrogen or in an air-tight 

 vessel in atmospheric air (in the latter case the oxygen was 

 probably soon converted into carbonic acid by the ripe fruits). 

 Although no trace of mould or other signs of the commence- 

 ment of decay could be recognized, 36 cub. centim. of distillate 

 contained 2'8 vol. per cent, of alcohol. 



Moreover plums which had been kept for an equal time in 

 pure oxygen (prepared by the ignition of chlorate of potash) 

 loith hydrate of potash also furnished an alcoholic distillate ; 

 nay, ripe figs which had lain in ozonized air showed signs of 

 alcoholic fermentation by their odour and the commencement 

 of yeast-formation in their cells. Under these circumstances 

 also, just as when they had lain in carbonic acid and in hydro- 

 gen gas, the fruits retained their normal sound appearance for 

 weeks, and were not attacked by mould, whilst other similar 

 fruits lying in the air had long been decayed and mouldy. 

 On those plums which, as described, had been preserved under 

 pure oxygen gas, a partial production of mould had certainly 

 commenced ; but for the purpose of distillation twenty-four 

 well-preserved fruits, of perfectly sound appearance, with no 

 signs of mould, were selected. Some similar fruits were ex- 

 amined microscopically, and proved to be free from Fungi in 

 the interior also. 



Even in those experiments which fm'nished a distillate with 

 a neutral reaction, alcohol was obtained, but 1 per cent, less 

 than in those in which carbonic acid was employed. Other 

 grapes and plums which were exposed to the atmosphere 

 showed no trace of alcohol even when distilled over platinum- 

 black. 



Consequently the fruits which in other respects 'appeared 

 sound, were affected and passed into alcoholic fermentation by 

 excessive action of oxygen just as by other gases injurious to 

 the normal assimilative activity, although (to judge from the 

 results of distillation) this occiu-s rather later in oxygen gas 

 than in the gases employed in the other experiments. 



The exclusion of oxygen, therefore, is not the immediate 

 cause of alcoholic fermentation and allied phenomena in the 



