36 



Report of Schimmel 8j Co. April/October 1917. 



In order to study the influence of the time the plants were harvested and the 

 quality of the material which was to be distilled, Rabak treated the plants not only 

 in the fruiting period, but also before and after they blossomed, in a fresh as well as 

 in a dry state. Whereas the oils from budding and from flowering plants showed 

 varying properties, those gathered from fruit- bearing plants were more uniform in 

 quality. The dried herb (with due regard for loss in weight) produced 50 per cent, 

 less oil than fresh, hence drying before distillation, according to Rabak, is to be 

 avoided. On the whole it appeared that the oil yield diminishes the more the plant 

 approaches maturity. The herb in a whole state produced less oil than the leaves 

 and stalk ends; the leaves contain most oil, the stalks hardly any. On the average 

 the oil yield from fresh, budding herb amounted to 0.134 per cent, from dry herb 

 to 0.66 per cent, from fresh flowering herb to 0.132 per cent, from dry ditto to 

 0.050 per cent, finally from fresh, fruit- bearing plants to 0.114 per cent, and from 

 dry ditto to 0.046 per cent 



From the entire fresh plants he obtained on distilling when budding 0.116 per cent, 

 during the blossom stage 0.113 percent, and while bearing fruit 0.133 percent The 

 leaves of plants produced before blossoming and distilled in a fresh state gave on an 

 average 0.203 per cent, of oil, those from blossoming plants 0.303 per cent, and those 

 from plants bearing fruit 0.120 per cent The tops, gathered from budding plants, 

 contained in a fresh state on an average 0.173 per cent, of oil, those from flowering 

 plants 0.233 per cent, and those from fruit-bearing plants 0.153 per cent 



Apparently the various vegetation stages of the plant itself have very little effect 

 on the colour, smell, or taste of the oil. Oils from flowering plants are specifically 

 heavier and show a lower rotation than those from plants before blossoming or in a 

 fruit-bearing stage. The oils vary exceedingly in reference to their solubility in 

 80 per cent alcohol. Oil from dry plants is generally darker in colour than that from 

 fresh plants and also has a less agreeable smell. The ester-content increases with 

 the development of the plant. Oils rich in esters frequently contain only little free 

 menthol and vice versa. Oils from dry plants are richer in free acids and esters than 

 those from fresh plants; drying seems to have a favourable effect on the production 

 of esters; apparently malodorous compounds, however, are formed thereby which 

 produce the bad smell, referred to above, of oils from dry plants. The formation of 



Table I. 



Yields and properties of peppermint oils grown on various soils. 



Locality and quality 



Yield 



d220 



«D 



" D 



Solubility in 

 80 per cent. 



acid *) 



ester 2 ) 



Menthol 

 content 



of soil 











alcohol 



content 



free 



total 



Arlington Farm (heavy, 



per 

 cent. 











per 

 cent. 



per 

 cent. 



per 

 cent. 



per 

 cent. 



clay soil 



0.12 



0.9203 



— 21.2 



1.4662 at 25° 



in 1.2 vols., becomes 



0.21 



7.07 



46.5 



51.7 





and 



and 



and 



and 



turbid in 2 vols., and 



and 



and 



and 



and 



. 



0.13 



0.9273 



-II.40 



1.4820 at 22° 



0.6 vol., becoming 

 turbid in 2.5 vols. 



0.03 



11.67 



30.94 



40.13 



Webster (rich black 





















loam) 



0.10 



0.9280 



— 16° 



1.4715 at 25° 



in 1.5 vols., becomes 

 turbid in 2.5 vols. 



0.05 



9.9 



46.48 



54.28 



Glenn Dale (light, 











and more 











sandy soil) 



0.11 



0.9403 



—20° 



1.4735 at 23° 



in 0.8 vol., becomes 



turbid in 2.5 vols. 



and more 



0.75 



23.34 



35.89 



54.28 



*) Calculated as free acetic acid. 



*) Calculated as menthyl acetate. 



